Home

Samurai 90-92 Supplelmentary Service Manual

image

Contents

1. Replace Poor _ relay to coupler connection B W wire open B wire open poor B15 connection or poor engine ground If all above are OK sub stitute a known good ECM and recheck 1 ECM coupler disconnected 2 Service wire To be continued 4A 35 Continued Poor connection at both B1 and B7 W wire open poor relay to coupler con Hf connection is OK check ECM and its nection or BI B wire open circuit referring to p 4A 73 If all above are OK check main relay refer ring to p 4A 98 Fig 4A 42 Diagnostic Flow Chart A 1 For ECM Power and Ground Circuit 4A 36 A 2 CHECK ENGINE LIGHT CIRCUIT CHECK CHECK ENGINE LIGHT DOESN T LIGHT AT IGNITION SWITCH ON THOUGH ENGINE STARTS Main fuse Ignition switch Circuit fuse CHECK ENGINE light bulb ECM 6 Combination meter AUN o 1 With ignition switch turned OFF disconnect coupler Green from ECM 2 Body ground terminal B13 in couper disconnected 3 Does CHECK ENGINE light turn ON at ignition switch ON 1 ECM coupler disconnected 2 Body ground Bulb burned out V Y wire circuit open or B W wire circuit open Poor B13 connection If connection is OK substi tute a known good ECM and recheck Fig 4A 44 Diagnostic Flow Chart A 2 for CHECK ENGINE Light Circuit 4A 3
2. Check vacuum hose and opener referring Vaccum hose mis connection leak to p 44 100 age clog or deter Are they in good ioration condition Defective opener Check VSV for resi stance and operation referring to p 4A 100 NO Faulty VSV Are they both in good condition ves 1 Connect coupler 2 Is battery voltage applied to ECM coupler terminal B14 at ignition switch ON ECM BI B wire open Lg W wire open To be continued 4A 68 ECM ECM coupler VSV Throttle opener Throttle valve Main switch Main retay Clutch switch Starter Vacuum hose WTS CAS Throttle opener system in good condition Body ground Lg W wire shorted to ground or Poor VSV coupler connection If wires and connections are OK substitute a known good ECM and recheck Continued Engine start signal not fed Is voltage at ECM coupler terminal B14 OV at engine crank ing Is battery voltage ap lied to ECM coupler terminal B11 at en gine cranking 2 Body ground Is ECM coupler con nected to ECM pro perly NO Poor ECM to ECM coupler connection Substitute a known good ECM and re check NOTE Before substituting a known good ECM check to make sure that resistance of co
3. Fuel leakage from injector Fuel leakage from between injector and throttle body Faulty fuel pump Faulty check valve in fuel pump Fuel leakage from fuel pressure regulator diaphragm High pressure 1 Disconnect fuel return hose from fuel pressure regulator and con nect new return hose to it 2 Insert the other end of new return hose into approved gasoline con tainer 3 Operate fuel pump ls specified fuel pressure obtained then NO Clogged fuel filter Restricted fuel feed line YES Restricted fuel return line Fig 4A 91 Diagnostic Flow Chart B 3 For Fuel Pressure Check 2 4A 67 B 4 THROTTLE OPENER SYSTEM CHECK 1 3 1s 2 2 3 ett eal 2 aS 5 i 6 i o 5 7 B11 f s y 7 of e 8 Mhhhdn a D 9 j 10 LILLE LLL LL Saar ra aay ara ar ar S 12 11 9 8 Fig 4A 92 Throttle Opener System Check throttle open er for operation re ferring to p 4A 100 Is it in good condi tion Faulty opener Warm up engine to normal operat ing temperature 2 Is throttle valve opened by throt tle opener at both engine stop and cranking Adjust throttle valve opening by throttle opener referring to p 4A 80 Check throttle vaive opening by throttle opener referring to p 44 80 Does throttle opener rod retract Q 1 second after engine start
4. Engine makes sharp metallic knocks that change with throttle opening Poor gasoline mileage 4A 62 Low fuel pressure Defective EGR system Defective injector Poor performance of TPS WTS or pressure sensor Faulty ECM Diagnostic flow chart B 3 Diagnostic flow chart B 6 Check injector for resistance injection condition and fuel leakage Refer to p 4A 87 See p 4A 91 44 94 or 4A 90 See p 4A 73 Diagnostic flow chart B 3 Diagnostic flow chart B 6 Check injector for resistfance injection condition and fuel leakage Refer to p 44 87 See p 4A 91 4A 94 or 4A 90 See p 44 73 High idle speed Fuel pressure out of specification of fuel leakage Faulty EGR system Defective injector Poor performance of TPS WTS or pressure sensor Faulty ECM Refer to item Improper engine idle speed previously Diagnostic flow chart B 3 Diagnostic flow chart B 6 Check injector for fuel leakage See p 4A 87 See p 4A 91 4A 94 or 4A 90 See p 4A 73 SYMPTOM POSSIBLE CAUSE INSPECTION Excessive hydrocar bons HC emission Rich or lean fuel mixture Excessive carbon monoxide CO emission Rich fuel mixture Faulty basic engine parts Clogged air cleaner vacuum leaks faulty ignition system engine compression etc Engine not at normal operating temperature Lead contamination of catalytic coverter Fuel leakage from injector
5. DIAGNOSTIC FLOW CHART NO Proceed to chart A 1 ECM power and ground circuit check Does engine start YES Proceed to chart A 2 CHECK ENGINE light circuit check NOTE If engine fails to start crank it for 2 seconds and then while keeping ignition switch ON Don t turn it OFF connect spare fuse to diagno sis switch terminal Proceed to chart A 3 CHECK ENGINE light circuit check Remains ON YES Proceed to TRO UBLE DIAGNO SIS p 44 60 Check Electronic Fue Injection sys tem parts that are not indicated by self diagnosis function Are engine basic parts described in SECTION 2 EN GINE DIAGNO SIS in good con dition Repair or replace 1 Fuse box 2 Diagnosis switch terminal NO Fig 4A 39 Diagnostic Flow Chart For Electronic Fuel Injection System 4A 33 DIAGNOSIS CODE TABLE EXAMPLE When throttle position sensor is defective Code No 21 Code No 21 Code No 21 Code No 21 p 1 CHECK ENGINE light turn ON OFF gt 0 3 0 3 1 0 0 3 A Time sec 0 3 DIAGNOSTIC CHECK ENGINE LIGHT CODENO FLASHING PATTERN DIAGNOSTIC ITEM DIAGNOSIS 13 Oxygen sensor 14 WTS 15 21 23 25 24 Diagnose trouble according to DIAGNOSTIC FLOW
6. e Fuel pressure out of specification e Poor performance of WTS ATS or pressure sensor Faulty ECM Faulty basic engine parts Clogged air cleaner vacuum leaks faulty ignition system engine compression etc Engine not at normal operating temperature Lead contamination of catalytic converter Fuel leakage from injector Fuel pressure out of specification High fuel pressure Poor performance of WTS ATS or pressure sensor Faulty ECM Check for absence of filler neck restrictor See p 4A 87 Diagnostic flow chart B 3 See p 4A 94 4A 94 or 4A 90 See p 4A 73 Check for absence of filler neck restrictor See p 44 87 Diagnostic flow chart B 3 See p 4A 94 4A 94 or 4A 90 See p 4A 73 Excessive nitrogen oxides NOx emission Lean fuel mixture Improper ignition timing Lead contamination of catalytic converter Misrouted vacuum hoses Defective EGR system Fuel pressure out of specfication Low fuel pressure Poor performance of WTS ATS or pressure sensor Faulty ECM See section 8 Check for absence of filler neck restrictor Diagnostic flow chart B 6 Diagnostic flow chart B 3 See p 4A 94 4A 94 or 4A 90 See p 44 73 4A 63 B 1 FUEL INJECTOR AND ITS CIRCUIT CHECK ENGINE NO STARTING ECM ECM coupler Injector Injector coupler wns Fig 4A 85 Injector Circuit Using sound scope check injector for operating s
7. 2 Is there continuity be tween ECM coupler ter minai AS and body ground Sb wire shorted to ground Substitute a known good ECM and recheck Fig 4A 82 Diagnostic Flow Chart For Code No 54 Not for California spec model 4A 58 CODE NO 71 TEST SWITCH CIRCUIT TEST SWITCH CIRCUIT GROUNDED FOR 5 SECONDS EVEN WHEN DRIVING AT 40 km h 25 mile h OR HIGHER 1 ECM 2 ECM coupler 3 Moniter coupler 4 Test switch terminal Fig 4A 83 Test Switch Circuit Is test switch terminal grounded with service wire NO YES 1 With ignition switch OFF disconnect ECM coupler 2 Is there continuity between ECM coupler terminal A7 and body ground 1 ECM coupler disconnected NO YES Substitute a known good ECM and recheck BI wire shorted to NOTE ground With California spec model intermittent trouble or faulty ECM Recheck referring to Intermittent trouble on p 44 31 Fig 4A 84 Diagnostic Flow Chart For Code No 71 4A 59 TROUBLE DIAGNOSIS This section describes trouble diagnosis of Elec tronic Fuel Injection system parts whose trouble is not indicated by the self diagnosis function SYMPTOM When diagnostic code No 12 is indicated by the self diagnosis function and assured y those en gine basic parts as described in ENGINE DIAGNOSIS are all in good condition check below Electronic Fuel Injection system parts which may be a
8. Coupler ECM coupler TO pressure sensor To other sensors QIAN Fig 4A 56 TPS Circuit 1 TPS coupler disconnected 2 Engine ground 1 Disconnect TPS coupler with ignition switch OFF 2 With ignition switch ON is voltage applied to Gr R wire terminal of TPS coupler about 4 5V Gr R wire open Gr R wire shorted to ground circuit or Gr Y wire or poor A23 connection if wire and connection are OK substitute a known good ECM and recheck Check TPS referring to p 44 91 Is it in good condition Faulty TPS Gr wire open Gr wire shorted to ground circuit poor TPS to TPS coupler connection or poor A21 connection if wire and connections are OK intermittent trouble or faulty ECM Recheck referring to Intermittent trouble on p 44 31 Fig 44 57 Diagnostic Flow Chart For Code No 22 4A 45 CODE NO 23 ATS AIR TEMPERATURE SENSOR CIRCUIT LOW TEMPERATURE INDICATED SIGNAL VOLTAGE HIGH ECM ECM coupler ATS ATS coupler To other sensors Fig 4A 58 ATS Circuit Disconnect ATS coupler with ignition switch OFF 2 With ignition switch ON check valtage at R B wire terminal of ATS coupler Is it about 4 5V 4 ATS coupler wire harness side 2 Engine ground 3 Voltmeter probe NO R B wire open poor A17 connection or R B wire short
9. NO YES Fuel pump circuit in good condition Turn OFF ignition switch Using service wire connect P B and B W wire terminals 3 Is fuel pump heard to operate at ignition switch ON 1 Fuel pump relay 2 Service wire YES no Check fuel pump relay referring to p 4A 99 P B wire open poor fuel pump coupler Is it in good condition connection or faulty fuel pump NO YES Poor relay coupler connection P wire open Faulty fuel pump relay or poor B16 connection If wire and connection are OK substitute a known good ECM and recheck NOTE Before substituting a known good ECM check to make sure that resistance of coil in relay is as specified Fig 4A 88 Diagnostic Flow Chart B 2 For Fuel Pump and Its Circuit Check 4A 65 B 3 FUEL PRESSURE CHECK Fuel pump Fuel filter Fuel injector Fuel pressure regulator Fuel pressure gauge Fig 4A 89 Fuel Pressure Check NOTE Before using following flow chart check to make sure that battery voltage is higher than 11V If battery voltage is low pressure be comes lower than specification even if fuel pump and line are in good condition 1 Install fuel pressure gauge referring to p 4A 81 No pressure 2 Operate fuel pump by turning ignition To A on next page switch ON Is fuel pressure then 2 4 2 8 kg cm 240 280 kPa 34 1 39 8 psi gt Also is 1 5 kg cm 150 kPa 21 3 ps
10. When the vehicle is at a stop the throttle valve is at the idle position and the engine is running ECM controls the bypass air flow by increasing or decreasing ON time of SC solenoid valve so that the engine speed is kept at a specified idle speed With an A C equipped vehicle when the A C is ON a certain amount of the bypass air is supplied by the A C VSV independently of this system The bypass air supplied by this system is used for fine control to keep the idle speed as specified A C OFF A C ON 1 000 50 Engine idle speed 800 50 specification r min r min 4A 25 Engine speed ae CAS Vehicl d ehicle spee vss Barometric pressure Pressure sensor Cooling water temp WTS Throttle valve opening TPs Engine start signal Engine start switch A C ON ional Sara A C amplifier Diagnosis signal Diagnosis switch A u erin Le SS ISC solenoid off valve 1 Throttle body ON time 2 ISC solenoid valve 3 Air cleaner 1 cycle constant Fig 4A 30 ISC Solenoid Valve Control System FUEL PUMP CONTROL SYSTEM ECM controls ON OFF operation of the fuel pump by turning it ON via the fuel pump relay under any of the following condition e For 3 seconds after ignition switch ON e While cranking engine while engine start signal is inputted to ECM e While CAS signal is inputted to ECM 1 Fuel pump 5 Main switch 2 CAS 6 ECM 3 Starter 7 Main relay 4 Clutch sw
11. engine ground 3 With ignition switch ON is 10 14V applied YES Poor igniter coupler connection If connection substitute a good igniter is OK known 4A 51 CODE NO 42 CAS CRANK ANGLE SENSOR SENSOR SIGNAL NOT INPUTTED FOR CIRCUIT 3 SECONDS AT ENGINE CRANKING ECM ECM coupler CAS in distributor Coupler To main relay SPO gt B2 B3 Bi0 ha a Fig 4A 70 CAS Circuit 1 With ignition switch OFF disconnect ECM coupler Yellow 2 Connect voltmeter between B1 terminal of ECM coupler Green and A13 termi nal of yellow coupler disconnected 3 Remove distributor cap rotor and shield cover 4 With ignition switch ON check voltage with signal rotor inserted between hall element and magnet A and without it B respectively Battery voltage er Is it in good condition 1 ECM 2 ECM coupler connected Green 3 ECM coupler disconnected Yellow Magnetic flux to hall Magnetic flux applied element cut off to hall sensor Battery BI R wire open B G wire open poor CAS coupler connection or faulty CAS voltage Poor A13 connection at both BI R wire short to ground or faulty CAS if connection is OK substitute a known A and good ECM and recheck p OV at both A and B Fig 4A 71 Diagnostic Flow Chart For Code No 42 4A 52 CODE NO 44 IDLE SWITCH CI
12. ine Gr G wire shorted to ground circuit If wire is OK intermittent trouble or faulty ECM Recheck referring to Intermittent trouble on p 4A 31 Faulty PS Fig 4A 67 Diagnostic Flow Chart For Code No 32 4A 50 CODE NO 41 IGNITION SIGNAL CIRCUIT IGNITION FAIL SAFE SIGNAL NOT INPUTTED 6 TIMES CONTINUOUSLY IGf BIG O 0 O O ha aaa Fig 4A 68 Ignition Signal Circuit Check ignition spark re ferring to SECTION 8 Is it in good condition 1 With ignition switch OFF disconnect ig niter coupler Connect voltmeter between Or wire terminal and engine ground Is following voltage is indicated under each condition Ignition switch ON Engine About cranking 4 5V NO Or wire open or poor A12 connection If wire and connection substitute a are OK known good ECM and recheck Fig 4A 69 Diagnostic Flow Chart For Code No 41 Igniter coupler disconnected Engine ground YES Faulty ignition coil faulty noise suppressor faulty Br W wire poor coupler connec tion or Faulty igniter OT RWN ECM ECM coupler Igniter Igniter coupler Ignition coil Noise suppressor NO Or B wire open or poor A6 connection If wire and connection are OK substitute a known good ECM YES With ignition switch OFF disconnect ig niter coupler 2 Connect voltmeter between Or B wire terminal and
13. to Gr Y wire or ground circuit lf wire is OK substitute a known good ECM and recheck Intermittent trouble or faulty ECM Recheck referring to Intermittent trouble on p 4A 31 Faulty WTS Fig 4A 53 Diagnostic Flow Chart For Code No 15 4A 43 CODE NO 21 TPS THROTTLE POSITION SENSOR CIRCUIT SIGNAL VOLTAGE HIGH ioe 4iGrR Ving 1 Ecm anger vouti ws ae arag BUN IDL N co 4 ECM coupler A24 J GY enD j 5 To pressure sensor 6 To other sensors Fig 44 54 TPS Circuit NOTE Be sure to turn OFF ignition switch for this check Disconnect TPS coupler Check TPS referring to p 4A 91 Is it in good condition Disconnect ECM coupler 2 With TPS coupler disconnected is there continuity between ECM coupler termi nals A23 and A21 NO Faulty TPS ECM coupler disconnected Disconnect PS pressure sensor coupler Connect TPS coupler Is resistance between ECM coupler termi nals A23 and A24 3 5 5 37 kQ Gr R wire short ed to Gr wire Wh Poor A24 connection If connection is OK intermittent trouble or faulty ECM Recheck referring to Intermittent trouble on p 4A 31 Gr Y wire open or poor TPS to Gr Y wire connec tion Fig 4A 55 Diagnostic Flow Chart For Code No 21 4A 44 CODE NO 22 TPS THROTTLE POSITION SENSOR CIRCUIT SIGNAL VOLTAGE LOW ECM TPS
14. 7 A 3 CHECK ENGINE LIGHT CIRCUIT CHECK CHECK ENGINE LIGHT DOESN T FLASH OR JUST REMAINS ON EVEN WITH SPARE FUSE CONNECTED TO DIAGNOSIS SWITCH TERMINAL peat fla OOD i CHECK ENGINE light ECM Diagnosis switch terminals Fuse box Moniter coupler Combination meter 9 Applicable only to Federal Mileage sensor spec model exclusive of Cancel switch those of California and Canada specifications ON OMA WH Fig 44 45 CHECK ENGINE Light Circuit For California and Canada Spec Model Wire harness Violet Yel low between CHECK ENGINE tight and termi nal B13 in ECM coupler shorted to ground 1 Disconnect ECM cou pier Green with igni tion switch turned OFF 2 Does CHECK EN GINE light turn ON at ignition switch ON Are couplers connected to ECM properly Poor connection 1 Ground terminal A3 with coupler connected to ECM 2 Does CHECK EN GINE light flash at ignition switch ON Poor body grounding Diagnosis ground circuit A3 ground open Defective spare fuse 2 Body ground Substitute a known good ECM and recheck Fig 4A 46 Diagnostic Flow Chart A 3 For CHECK ENGINE Light Circuit For California and Canada spec model 4A 38 For Federal Spec Mode Except California and Canada Provide maintenance serv ice Re
15. 84 See p 4A 101 Diagnostic flow chart B 3 Check injector for resistance injection condition and fuel leakage Refer to p 4A 87 SYMPTOM POSSIBLE CAUSE INSPECTION Engine fails to idle NOTE Poor performance of WTS ATS or pressure sensor Faulty ECM If engine fails to idle when it is cold check air valve first See p 44 94 4A 94 4A 90 See p 4A 73 speed NOTE Improper engine idle e 0 9 Maladjusted accelerator cable play Clogged pressure sensor vacuum passage Faulty throttle opener system Faulty ISC solenoid valve control system Faulty A C VSV Maladjusted idle speed adjusting screw Faulty air valve Fuel pressure out of specification Faulty injector Poor performance of WTS ATS or pressure sensor Faulty ECM If engine idle speed lowers below specification only when electric load e g headlight ON check ISC solenoid valve control system first Engine has no or poor power Clogged pressure sensor vacuum passage e Maladjusted accelerator cable play Maladjusted installation angle of throttle position sensor Fuel pressure out of specification Low fuel pressure Faulty EGR system Faulty injector Poor performance of TPS WTS ATS or pressure sensor Faulty ECM See p 4A 78 Check vacuum hose and filter Diagnostic flow chart B 4 Diagnostic f
16. CHART corresponding to each code No 31 Pressure sensor 32 41 Ignition signal CAS Idle switch of TPS _ EGR system For California spec model only Ground circuit For Califor nia spec model only 5th switch Not for California spec model Test switch terminal ECM ECM failure Normal This code appears when none of the other codes Above codes are identified Fig 4A 40 Diagnostic Code Table 4A 34 A 1 ECM POWER AND GROUND CIRCUIT CHECK CHECK ENGINE LIGHT DOESN T LIGHT AT IGNITION SWITCH ON AND ENGINE DOESN T START THOUGH IT IS CRANKED UP 1 Fusible link 5 Main relay 2 Ignition switch 6 ECM 3 Circuit fuse for ignition 7 Engine ground for ECM coil 8 Terminal position of 3 1 Circuit fuse for ECM coupler viewed from 4 Fuse box wire side Fig 4A 41 ECM Power and Ground Circuit Is operation of main relay heard at ignition switch ON Are fusible link and circuit fuse for ignition cail in good condition Is circuit fuse for ECM in good condition NO Repair and replace Repair and replace Is main relay in good condition Check main relay re ferring to p 44 98 1 Disconnect ECMcou pler Green with ig nition switch OFF 2 Using service wire ground B15 terminal 3 Is battery voltage applied to B1 or B7 terminal at ignition switch ON
17. CIRCUIT SIGNAL VOLTAGE LOW AND DOESN T CHANGE NOTE Before diagnosing trouble according to flow chart given below check to make sure that following system and parts other than Electronic Fuel Injection system are in good condition Air cleaner clogged Vacuum leaks air inhaling Spark plugs contamination gap High tension cords crack deterioration Distributor rotor or cap wear crack ignition timing 1 ECM Engine compression e PENSE Any other system and parts which might affect A F 4 ECM coupler mixture or combustion If code No 13 and another code No are indicated toge ther the latter has priority Therefore check and correct Fig 4A 48 Oxygen Sensor Circuit what is represented by that code No first and then pro ceed to the following check Warm up engine to normal operating temperature 2 Remove seal from oxygen sensor coupler 3 Connect voltmeter between oxygen sensor terminal and engine ground 4 Maintain engine speed at 2000 r min After 60 seconds check voltmeter Oxygen sensor Coupler Seal Engine ground awn Remains unchanged Remains unchanged Deflects between at below 0 45V at above 0 45V above and below 0 45V repeatedly Replace oxygen sen To on next To on next Oxygen sensor and sor and recheck page page its circuit A F ratio feed back system are in good condition lntermittent trou ble or f
18. N check voltage at R Y wire terminal of WTS coupler is it about 4 5V 1 WTS coupler disconnected 2 Engine ground R Y wire open poor A18 connection or R Y wire shorted to power circuit If wire and connection are OK substitute a known good ECM and recheck Using service wire connect WTS coupler terminals 2 Check voltage at R Y wire terminal of WTS coupler with ignition switch ON Is it below 0 15V t WTS coupler disconnected 2 Service wire 3 Engine ground Gr Y wire open or poor A24 connection lf wire and connection are OK faulty ECM Substitute a known good ECM and recheck Poor WTS to WTS coupler connection or faulty WTS If connection and WTS are OK intermittent trouble or faulty ECM Recheck referring to Intermittent trouble on Fig 44 31 Fig 4A 57 Diagnostic Flow Chart For Code No 14 4A 42 CODE NO 15 WTS WATER TEMPERATURE SENSOR CIRCUIT HIGH TEMPERATURE INDICATED SIGNAL VOLTAGE LOW R Y 1 ECM 2 WTS aut 3 3 Coupler 2 4 ECM coupler 5 To other sensors Fig 4A 52 WTS Circuit 1 Disconnect WTS coupler with ignition switch OFF 2 With ignition switch ON is voltage applied to R Y wire terminal of WTS coupler 4V or more 1 WTS coupler disconnected 2 Engine ground Check WTS referring to p 4A 94 ts it in good condition R Y wire shorted
19. RCUIT CIRCUIT OPEN OR TPS INSTALLATION ANGLE MALADJUSTED L2 1Gr R_ Vind er vor 1 ECM mak BIW IDL leet 3 Po coupler 4 ae SND H 4 TPS coupler 5 Idle switch 6 To other sensors Fig 4A 72 Idle Switch Circuit Check idle switch in TPS referring to p 4A 91 Is it in good condition BI W wire open Gr Y wire open poor A14 connection poor A24 connection or poor TPS coupler connection If wires and connections are OK substitute a known good ECM and recheck Faulty idle switch or TPS installation angle maladjusted Fig 4A 73 Diagnostic Flow Chart For Code No 44 4A 53 CODE NO 45 IDLE SWITCH CIRCUIT CIRCUIT SHORT OR TPS INSTALLATION ANGLE MALADJUSTED 1 M Sue Ving 2 aa coupler rer vou N I A a BIW IDL ips 4 TPS coupler GAY GND 1 5 5 Idle switch in TPS an 6 To other sensors Fig 4A 74 Idle Switch Circuit Check idle switch in TPS referring to p 44 91 Is it in good condition YES NO BI W wire shorted to Gr Y wire or Faulty idle switch or TPS installation angle ground maladjusted If wire are OK intermittent trouble or faulty ECM Recheck referring to Intermit tent trouble on p 4A 31 Fig 4A 75 Diagnostic Flow Chart For Code No 45 4A 54 CODE NO 51 EGR SYSTEM AND REGTS RECIRCULATED EXHAUST GAS TEMPERATURE SENSOR CIRCUIT LOW TEMPERATURE INDICATED California spec mode
20. aulty ECM Recheck referring to item Inter mittent trouble on p 4A 31 4A 40 CODE NO 13 OXYGEN SENSOR CIRCUIT Continued Q Remains unchanged at below 0 45V Maintain engine speed at 2000 r min After 60 seconds discon nect vacuum hose from pressure sensor and check voltmeter Is voltage 0 45V or more Replace oxygen sensor and recheck Wire between sensor and ECM open poor A19 connection or lean A F mixture 1 If wire and connection are OK check pressure sensor WTS ATS fuel pressure and injector 2 If all above are OK check ECM and its circuit referring to p 4A 73 Fig 4A 49 Diagnostic Flow Chart For Code No 13 2 Remains unchanged at above 0 45V Oxygen sensor is in good condition Wire between sensor and ECM open poor A19 connection or rich A F mixture 1 If wire and connection are OK check TPS pressure sensor and its hose ATS WTS fuel pressure and injector 2 If all above are OK check ECM and its circuit referring to p 4A 73 4A 41 CODE NO 14 WTS WATER TEMPERATURE SENSOR CIRCUIT LOW TEMPERATURE INDICATED SIGNAL VOLTAGE HIGH 1 ECM NOTE 2 WTS When Code Nos 14 21 23 31 and 44 me Steel l are indicated together it is possible that es a Gr Y wire is open or A24 terminal connection is poor Fig 4A 50 WTS Circuit Disconnect WTS coupler with ignition switch OFF 2 With ignition switch O
21. e B Throttle body Throttle valve Rod Diaphragm Throttle opener Spring VSV ECM Main relay Ignition switch Sensed information 1 2 3 4 5 6 7 8 9 0 Fig 4A 32 Throttle Opener Control System 4A 27 EXHAUST GAS RECIRCULATION EGR CONTROL SYSTEM This system controls the formation of NOx emission by recirculating the exhaust gas into the combustion chamber through the intake manifold The EGR valve is controlled by EGR modulator and VSV controlled by ECM according to signals from various sensors The diaphragm mounted in the EGR modulator is operated by back pressure of the exhaust gas to open and close the valve By this opening and closing action of the valve the EGR modulator controls the vacuum transmitted to the EGR valve Under a low load condition such as low speed driving the exhaust pressure is low In this state the diaphragm in the EGR modulator is pushed down by the spring force and the modulator valve opens to allow the air into the vacuum passage from the outside As a result the vacuum transmitted to the EGR valve becomes smaller and so does the opening of the EGR valve Thus less amount of exhaust gas is recirculated to the intake manifold Under a high load condition such as high speed driving on the other hand the exhaust pressure is high By the high exhaust pressure the dia phragm in the modulator is pushed up and closes its valve As the air does
22. ed to power circuit If wire and connection are OK substitute a known good ECM and recheck Using service wire connect ATS coupler terminals 2 Check voltage at R B wire terminal of ATS coupler with ignition switch ON Is it below 0 15V 1 ATS coupler wire harness side 2 Service wire Gr Y wire open or poor A24 connection If wire and connection are OK substitute a known good ECM and recheck Faulty ATS or poor ATS coupler connec tion tf ATS and connection are OK intermittent trouble or faulty ECM Recheck referring to Intermittent trouble on p 4A 31 Fig 44 59 Diagnostic Flow Chart For Code No 23 4A 46 CODE NO 25 ATS AIR TEMPERATURE SENSOR CIRCUIT HIGH TEMPERATURE INDICATED SIGNAL VOLTAGE LOW ECM ECM coupler VSS ATS coupler To other sensors 1 2 3 4 5 Fig 4A 60 ATS Circuit 1 Disconnect ATS coupler with ignition switch OFF 2 With ignition switch ON is voltage applied to R B wire terminal of ATS coupler 4V or more ATS coupler wire harness side 2 Engine ground YES NO Check ATS referring to p 4A 94 R B wire shorted to ground circuit Is it in good condition If wire is OK substitute a known good ECM and recheck NO YES Intermittent troubie or faulty ECM Faulty ATS Recheck referring to Intermittent trouble on p 4A 31 Fig 4A 61 Diagnostic Flow Chart For Code N
23. el ratio compensation The air fuel ratio may vary due to such factors as variation in each engine itself and aging To compensate such variation feed back compensa tion is used and base air fuel mixture ratio is adjusted to a proper level Fuel cut When decelerating quickly the fuel supply is cut or decreased to prevent unburned gas from being emitted by making the injector operating time as ineffective injection time Also when the engine speed exceeds 6 800 r min the fuel supply is cut to protect the engine by making the injector operating time as ineffective injection time The normal injection is restored when the engine speed is 6 500 r min or lower 44 23 Fuel feed back compensation Air fuel ratio compensation It is necessary to keep the air fuel mixture close to the theoretical air fuel ratio 14 7 to obtain efficient performance of the 3 way catalyst and high clarification rate of CO HC and NOx in the exhaust gas For that purpose ECM operates as follows It first compares the signal from the oxygen sensor with a specified reference voltage and if the signal is higher it detects that the air fuel ratio is richer than the theoretical air fuel ratio and reduces fuel On the other hand if the signal is lower it detects that the air fuel ratio is leaner and increases fuel By repeating these operations it adjusts the air fuel ratio closer to the theoreti cal air fuel ratio 1 When oxygen concentration in the exhaust gas i
24. fer to SECTION OB Is odometer reading 50 000 80 000 or 100 000 miles CHECK ENGINE light circuit in good condition Move back to DIAGNOS TIC FLOW CHART onp 4A 33 Does CHECK ENGINE light flash when cancel switch is moved to the right or left Disconnect ECM cou pler Green with igni tion switch turned OFF 2 Does CHECK EN GINE light turn ON at ignition switch ON 1 Disconnect blue wire coupler of cancel switch with ignition switch turned OFF and ECM coupler disconnected 2 Does CHECK EN GINE light turn ON at ignition switch ON Defective cancel switch Circuit between CHE CK ENGINE light and cancel switch shorted to ground Poor connection Are couplers connected to ECM properly Ground terminal A3 with couplers connect ed to ECM 2 Does CHECK EN GINE light flash at ignition switch ON Poor body grounding Diagnosis ground circuit A3 ground open Defective spare fuse NO Substitute a known good ECM and recheck 2 Body ground Wire harness Violet Yel low between CHECK ENGINE light and termi nal B13 in ECM coupler shorted to ground Fig 44 47 Diagnostic Flow Chart A 3 For CHECK ENGINE Light Circuit For Federal spec model Except California and Canada 4A 39 CODE NO 13 OXYGEN SENSOR
25. from vacuum leakage and adjust it If duty remains un changed even when adjusting screw is turned check duty check terminal cir cuit 3 LOW IDLE SPEED 1 Disconnect SC hose from air cleaner case 2 Then is air drawn into it Check ISC solenoid valve for its resistance and operation Refer to p 4A 99 Is it in good condition Clogged ISC hose Lg B wire open or Poor coupler connec tions If all above are OK substitute a known good ECM and re check Adjust duty and idle speed referring to p solenoid HIGH IDLE SPEED 1 Block ISC solenoid valve hose by pinch ing it 2 Does engine speed reduce then Check ISC solenoid val ve for its resistance and operation Refer to p 4A 99 Is it in good condition 1 Check that air intake system including A C VSV is free from vacuum leakage 2 Adjust duty and idle speed referring to p 4A 78 NOTE If not adjustable with idle speed adjusting screw check air valve NO Faulty ISC solenoid valve Lg B wire shorted to ground if wire is OK sub stitute a known good ECM and recheck Fig 4A 96 Diagnostic Flow Chart B 5 For ISC Solenoid Valve Control System 2 4A 71
26. i or higher fuel pressure retained for 1 minute after fuel pump is stopped Pressure within spec but not retained To 2 on next page NO YES Low pressure To G on next page High pressure To on next page YES NO Normal fuel pressure Start engine and warm it up to normal operating temperature 2 Keep it running at specified idle speed Is fuel pressure then 1 7 2 1 kg cm 170 210 kPa 24 2 29 9 psi Clogged vacuum passage for fuel pressure regulator or Faulty fuel pressure regulator Fig 4A 90 Diagnostic Flow Chart B 3 For Fuel Pressure Check 7 4A 66 B 3 FUEL PRESSURE CHECK Continued D Shortage of fuel Fuel pump or its circuit defective Refer to Diagnostic Flow Chart B 2 Low pressure Operate fuel pump 2 With fuel return hose blocked by pinching it check fuel pressure Is it 4 0 kg cm 400 kPa 56 9 psi or more Faulty fuel pump Fuel leakage from hose connec tion in fuel tank Faulty fuel pressure regulator D Pressure within spec but not re tained Is there fuel leakage from fuel feed line hose pipe or their joint YES Fuel leakage Check again if specified pressure is retained While doing so disconnect fuel re turn hose from fuel return pipe Does fuel come out of return hose then Fualty fuel pressure regulator
27. il in VSV is as speci fied ECM in good condi tion Fig 4A 93 Diagnostic Flow Chart B 4 For Throttle Opener System 4A 69 B 5 ISC SOLENOID VALVE CONTROL SYSTEM CHECK Warm up engine to normal operating temperature and keep it idle 2 Connect spare fuse to diagnosis switch terminal 3 Is diagnostic code No 12 indicated YES Check ISC duty and idle speed referring to p 4A 78 Are they within specification YES System in good condition NO ISC sotenoid valve ECM Sensed information Moniter coupler Main relay A C VSV if equipped A C amplifier if equipped Duty check terminal Diag switch terminal Ground terminal Test switch terminal oop NO Go back to Diagnostic Flow Chart on p 4A 33 Idle speed is within specification but duty is not To 1 on next page High idle speed To on next page Low idle speed To 8 on next page Fig 44 95 Diagnostic Flow Chart B 5 For ISC Solenoid Valve Control System 1 4A 70 B 5 ISC SOLENOID VALVE CONTROL SYSTEM CHECK Continued idle speed is within specification but duty is not Adjust ISC duty to spe cification referring to p 4A 78 NOTE When ON duty of ISC is close to 0 but close to 100 with such duty meter that indicates OFF duty in other words when ISC is almost fully closed check that air intake system is free
28. injection Time amount of injection The factors to determine the injection time are the basic injection time which is calculated on the basis of the engine speed and the intake manifold pressure amount of the intake air and various compensations which are determined according to the signals from various sensors that detect the state of the engine and driving conditions NOTE The amount of fuel drawn into the engine is determined by the injection frequency as well as injection time Engine speed Basic injection Intake manifold time pressure Injection time Pressure sensor Intake air temperature Cooling water temperature Throttle valve opening and operation Compensation Supply voltage Battery Engine start switch Engine start signal Main switch O2 concentration Oxygen sensor Clutch engagement Clutch switch ON OFF signal A C amplifier Fig 4A 28 2 Parameter Diagram 4A 22 Intake air temperature compensation As the intake air volume varies with the tem perature it is compensated for its temperature Enriching compensation while warming up When the engine is cold enriching compensa tion is made to ensure good driveability till the engine cooling water temperature reaches the specified level The amount to enrich the air fuel mixture is decreased as the temperature rises Enriching compensation after engine start For a certain time after the engine is started air fuel mixture enriching com
29. itch 8 Fuel pump relay Fig 4A 31 Fuel Pump Circuit 4A 26 THROTTLE OPENER CONTROL SYSTEM In this system the throttle valve is opened a little wider than the idle position to improve the engine performance at its start The throttle opener is controlled by VSV Vacuum Switching Valve which opens and closes the vacuum passage to the throttle opener ECM controls VSV according to the engine speed starter signal and signal from the WTS and turns ON the electric circuit of VSV when the engine is cranking e the engine speed is less than 4 000 r min for O to some ten seconds after the engine start duration time depends on the cooling water temperature e g shorter for higher cooling water temperature In either of the above conditions VSV opens between the filter and passage A and closes between passages A and B In this state like when the engine is at a stop the chamber C of the throttle opener is under the atmospheric pressure It means that the spring force pushes the rod to open the throttie valve Once the engine starts to run ECM turns OFF the electric circuit of VSV which then opens between passages A and B and closes between the filter and passage A Consequently the vacuum in the intake manifold is applied to the chamber C of the throttle opener and the diaphragm and rod are pull ed In this way the throttle valve moves back to its idle position Filter Passag
30. its coupler is disconnected Attempt to do it may cause damage to ECM Never connect an ohmmeter to ECM with its coupler connected to it Attempt to do it may cause damage to ECM and sensors Be sure to use a voltmeter with high impedan ce MQ V minimum or a digital type vol tmeter Any other voltmeter should not be used because accurate measurements are not obtained 4A 31 When checking voltage at each terminal of the coupler which is connected to ECM be sure to negative probe to body ground Any other way is prohibited even by accident Applying it improperly may cause the sensor or ECM to be shorted and damaged ECM ECM coupler Yellow ECM coupler Green Body ground rj fang fob ov Fig 4A 35 Checking Voltage and Terminal Position e For ECM coupler terminal positions A1 A2 to A24 and B1 B2 to B17 refer to Fig 4A 35 e When disconnecting and connecting coupler make sure to turn ignition switch OFF e When there is a question Are couplers con nected properly in FLOW CHART check male half of terminal for bend and female half for excessive opening terminal for poor locking looseness corrosion dust etc When connecting a probe of ohmmeter volt meter etc to coupler terminal be sure to connect it from wire harness side of coupler 4A 32 1 Coupler 2 Probe Fig 4A 36 Connecting Meter Probe When connecting meter probe from terminal side
31. l only 1 REGTS 2 Coupler 9 3 EGR valve 4 EGR modulator 5 EGR VSV 6 ECM 7 Main relay 8 Sensed information 9 To other sensors of FLA EB NEP 11 12 t 13 Fig 4A 76 EGR System California spec model only Check EGR system referring to p 44 101 Is it in good condition NO YES Check vacuum hose EGR valve and EGR modulator referring to p 4A 102 Are they in good condition Check REGTS circuit Proceed to next page YES NO Check EGR VSV referring to p 44 103 Vacuum hose misconnection leakage or clog Is it in good condition faulty EGR valve or faulty EGR modulator YES NO Faulty VSV Lg Y wire open Lg Y wire shorted to ground poor VSV coupler connection or poor B5 connection If all above are OK substitute a known good ECM and recheck Fig 44 77 Diagnostic Flow Chart For Code No 51 1 California spec model only 4A 55 CODE NO 51 CONTINUED REGTS circuit check Disconnect REGTS coupler with ignition switch OFF 2 Is voltage at R G wire terminal about 4 5V at ignition switch ON YES Check REGTS referring to p 44 95 Is it in good condition YES Gr Y wire open poor A24 connection or poor REGTS coupler connection If all above are OK intermittent trouble or fauity ECM Recheck referring to Intermittent trouble on Pp 4A 31 R G wire 1 REGTS coupler wire harness side 2 Engine g
32. low chart B 5 See p 4A 78 See p 4A 84 Diagnostic flow chart B 3 Check injector for resistance injection condition and fuel leakage Refer to p 44 87 See p 4A 94 4A 94 or 4A 90 See p 4A 73 Check vacuum hose and filter See p 4A 78 See p 4A 92 Diagnostic flow chart B 3 Diagnostic flow chart B 6 Check injector for resistance injection condition and fuel leakage Refer to p 4A 87 See p 4A 91 4A 94 4A 94 or 4A 90 See p 4A 73 4A 61 SYMPTOM POSSIBLE CAUSE Engine hesitates when acceleration Clogged pressure sensor vacuum passage Defective throttle valve operation Poor performance TPS Fue pressure out of specification Low fuel pressure e Faulty EGR system e Faulty injector Poor performance of WTS or pressure sensor Faulty ECM INSPECTION OE Check vacuum hose and filter Check throttle valve for smooth operation See p 4A 91 Diagnostic flow chart B 3 Diagnostic flow chart B 6 Check injector for resistance injection condition and fuel leakage Refer to p 4A 87 See p 4A 94 or 4A 90 See p 4A 73 eee Surges e Variation in vehicle speed is felt although accelerator pedal is not operated Variable fuel pressure Clogged fuel filter defective fuel pressure regulator etc Defective EGR system Defective injector Poor performance of TPS WTS or pressure sensor Faulty ECM Excessive detonation
33. n accident be sure to follow instructions given below when checking by using Diagnostic Flow Chart When trouble can be identified that is it is not an intermittent one Check sensor actuator wires and each connection and if they are all in good con dition substitute a known good ECM and recheck When trouble can not be identified but CHECK ENGINE light indicates a trouble code Diagnose trouble by using that code No and if sensor actuator wires and each connec tion are all in good condition erase diagnos tic code in ECM memory Then conduct a test run and check what CHECK ENGINE light indicates Only when it indicates trou ble code again substitute a known good ECM and check again If it indicates not trouble code but normal code No 12 it means that an intermittent trouble did occur and has gone In this case check wires and connections carefully again NOTES ON SYSTEM CIRCUIT INSPECTION e Intermittent trobles Most intermittent problems are caused by faulty electrical connections or wiring Perform careful check of suspect circuits for Poor mating of coupler halves or terminals not fully seated in coupler body backed out Improperly formed or damaged terminals All coupler terminals in problem circuit should be carefully reformed to increase contact tension Poor terminal to wire connection Never connect any tester voltmeter ohmme ter or whatever to ECM when
34. nerated in the ignition coil to a proper level ESA system controls the time of primary current flow to the ignition coil NOTE The ignition timing is controlled by ECM as described above Therefore when checking or adjusting the ignition timing the ignition timing must be fixed by grounding the test switch terminal DIAGNOSIS ECM has a system self diagnosis function as des cribed previously p 4A 15 Investigate where the trouble is by referring to the following Diagnostic Flow Chart and Diagnostic Code PRECAUTIONS IN DIAGNOSING TROUBLES PRECAUTIONS IN IDENTIFYING DIAGNOS TIC CODE Before identifying diagnostic code indicated by CHECK ENGINE light don t disconnect couplers from ECM battery cable from bat tery ECM ground wire harness from engine Such disconnection will erase memorized trouble in ECM memory e If abnormality or malfunction lies in two or more areas CHECK ENGINE light indicates applicable codes three times each And flashing of these codes is repeated as long as diagnosis terminal is grounded spare fuse is connected and ignition switch is held at ON position Take a note of diagnostic code indicated first INTERMITTENT TROUBLES There are cases where CHECK ENGINE light indicates a diagnostic code representing a trouble which occurred only temporarily and has gone In such case it may occur that good parts are replaced unnecessarily To prevent such a
35. not enter the vacuum passage in this state the vacuum transmitted to the EGR valve grows larger and so does the opening of the EGR valve Thus larger amount of exhaust gas is recirculated to the intake manifold Under any one of the following conditions ECM closes the vacuum passage of VSV In this state as the vacuum is not transmitted to the EGR valve it remains closed 4A 28 When engine cooling water temperature is low When barometric pressure is low at high alti tude When engine is running at high load When transmission is in 5th gear condition Not for California spec model Other than the above EGR valve opens and closes in accordance with the EGR modulator Operation Only California spec model is equipped with REGTS Recirculated Exhaust Gas Temperature Sensor The operation of EGR valves is monitored by ECM through the signal from the REGTS which Measures the temperature in the exhaust passage Should anyting abnormal occur CHECK ENGINE light turns ON to warn it Pressure sensor CAS TPS 5th switch Not for Catifornia spec model 1 t nan per 2 77 je ENE Nase ef 4 ignition switch Main relay ECM Sensed information VSV EGR modulator EGR valve REGTS California spec model only Intake manifold Throttle body Exhaust gas Vacuum Air SNAMRAN gt Fig 4A 33 EGR Control System 4A 29 ESA ELECTRONIC SPARK ADVANCE SYSTEM This system co
36. ntrols electronically the time of electric current flow to ignition primary coil as well as ignition timing ECM judges the engine condition by using signals from various sensors selects the most suitable electric current flow time and ignition timing for that engine condition from among those pre stored in its memory and sends a signal to the igniter power unit The igniter turns ON and OFF the primary current of the ignition coil according to the signal from ECM Control of this system includes four different types as follows Ignition timing control at engine start Ignition timing contro after engine start Electric current flow time control IGNITION K TIMING CONTROL IGf Ignition fail safe signal IGt Ignition 1 Igniter 6 TPS trigger 2 Ignition coil 7 WTS signat 3 Distributor 8 Engine start switch 4 CAS 9 Battery voltage 5 PS 10 Test switch terminal Fig 4A 34 System Diagram 4A 30 Ignition Timing Control at Engine Start To obtain better starting performance of the engine at the engine start when the engine start switch is turned ON or the engine speed is lower than 400 r min ESA system sets the ignition timing to BTDC 5 Ignition Timing Control After Engine Start Under any conditions other than engine start the ignition timing is determined according to the intake manifold pressure and the engine speed Electric Current Flow Time Control To stabilize the secondary voltage ge
37. o 25 4A 47 CODE NO 24 VSS VEHICLE VEHICLE SPEED LOWER THAN 1 4 km h 0 9 mile h SPEED SENSOR ALTHOUGH FUEL IS KEPT CUT FOR LONGER CIRCUIT THAN 10 SECONDS ECM ECM coupler VSS Speedometer Coupler ohh NOTE Be sure to turn OFF ignition switch for this check Fig 4A 62 VSS Circuit Does speedometer indicate vehicle speed NO Speedometer cable broken 1 ECM coupler disconnected 2 Body ground YES Disconnect ECM coupler with ignition switch OFF 2 Connect ohmmeter between A15 termi nal of ECM coupler and body ground 3 Hoist rear end of car and lock rear left tire 4 Turn rear right tire slowly Does ohm meter indicator deflect between 0 and a few times while tire is turned one re volution Check VSS referring to p 4A 96 Is it in good condition Poor A15 connection If connection is OK intermittent trouble or faulty ECM Recheck referring to Intermittent trouble on p 44 31 Faulty VSS Br Y wire open B wire open poor coupler to meter connection or poor B wire ground Fig 4A 63 Diagnostic Flow Chart For Code No 24 4A 48 CODE NO 31 PS PRESSURE SENSOR CIRCUIT SIGNAL VOLTAGE HIGH HIGH PRESSURE LOW VACUUM ECM ECM coupler PS PS coupler To TPS To other sensors AARON Fig 4A 64 PS Circuit 1 Disconnect PS coupler with ignition
38. of coupler because it can t be connected from harness side use extra care not to bend maie terminal of coupler or force its female terminal open for connection In case of such coupler as shown below con nect probe as shown below to avoid opening female terminal Never connect probe where male terminal is supposed to fit Coupler Probe Where male terminal fits ow Fig 44 37 Connecting Meter Probe e Before measuring voltage at each terminal check to make sure that battery voltage is 11V or higher Such terminal voltage check at low battery voltage will lead to erroneous dia gnosis Fig 4A 38 Checking Battery Voltage Does light turn ON when ignition switch is turned ON without starting engine START CHECK ENGINE YES Connect spare fuse to dia gnosis terminal observe switch grounding and CHECK ENGINE light Flashes Is diagnostic code No 12 in dicated Check and repair according to flow chart corresponding to that code No After repair disconnect battery negative cable for longer than 20 sec to erase diagnostic code stor ed in ECM memory and reconnect it Start engine and warm it up to normal operat ing temperature With spare fuse connect ed to diagnosis terminal and ignition switch turn ed ON make sure that CHECK ENGINE light shows code No 12 Disconnect spare fuse from diagnosis terminal Is trouble corrected
39. ound at engine cranking Is it detected Is fuel injected from injector at engine cranking Refer to p 44 87 for checking proce dure Does injector inject fuel properly Refer to p 4A 87 for checking proce dure Disconnect injec tor coupler 2 Is resistance of in jector 0 8 1 82 at 20 C 68 F Does fuel leak from injector after injec tion at a rate of higher than 1 drop min 1 Connect injector coupler 2 Disconnect ECM coupler from ECM with ignition swi tch turned OFF 3 Is resistance be tween B8 and B17 terminals of dis connected ECM coupler 0 8 1 8 Q at 20 C 68 F Injector and its cir cuit in good condi tion 1 Disconnected ECM coupler Red or Yellow wire open Red wire shorted to Yellow wire or ground Poor connection of injector cou pler Poor connection Is ECM coupler con nected to ECM pro perly Substitute a known good ECM and re check Fig 44 86 Diagnostic Flow Chart B 1 For injector and ts Circuit 4A 64 Check fuel pump and fuel pressure Proceed to DIA GNOSTIC FLOW CHARTS B 2 and B 3 B 2 FUEL PUMP CIRCUIT CHECK ECM ECM coupler Fuel pump relay Fuel pump Main relay kWh Fig 4A 87 Fuel Pump Circuit Is fuel pump heard to operate for 3 sec after ignition switch ON
40. pensation is made so as to stabilize the engine speed As the amount of compensation depends on the engine cooling water temperature it is the largest immediately after the engine start and after that it reduces gradually Enriching compensation while loaded high Enriching compensation is made to make the air fuel mixture ratio richer than the theoretical air fuel mixture ratio to ensure good driveability under highly loaded driving condition Enriching compensation when accelerating To attain smooth acceleration enriching com pensation is provided for a certain time accord ing to each accelerating condition which is ob tained through operation using the signal from the pressure sensor representing variation of pressure in the intake manifold Leaning compensation when decelerating To obtain a proper air fuel mixture ratio during moderate deceleration compensation is made for a certain time so that the air fuel mixture jeans out to a proper ratio for each decelerating condition which is obtained through operation using the signal from the throttle position sensor representing variation of throttle valve opening Battery voltage compensation A power voltage drop delays the mechanical operation of the injector Then the actual injec tion time becomes shorter for the time that ele ctricity is supplied to the injector To compensate this the electricity supply time is made longer when the voltage is lower Base air fu
41. possible cause for each symptom of the engine POSSIBLE CAUSE INSPECTION Hard or no starting Engine cranks OK NOTE Shortage of fuel in fuel tank Faulty fuel pump or its circuit open Injector or its circuit defective Fuel pressure out of specification Faulty air valve Open starter signal circuit Faulty throttle opener system Poor performance of WTS ATS or pressure sensor e Fauity ECM Check if fuel pressure is felt at fuel return hose for 3 seconds after ignition switch ON tf not advance to Diagnostic flow chart B 2 Diagnostic flow chart B 1 Diagnostic flow chart B 3 See p 4A 84 Check voltage at ECM cou pler terminal B11 refer to p 44 73 Diagnostic flow chart B 4 See p 4A 94 4A 94 or 44 90 See p 4A 73 f engine doesn t start at all perform fuel injector and its circuit check first Advance to Diagnostic flow chart B 1 o If engine is hard to start only when it is cold check air valve first and then engine starter signal circuit e If engine starts easily with help of accelerator pedal operation check throttle opener system first Advance to Diagnostic flow chart B 4 Engine fails to idle 4A 60 Shortage of fuel in fuel tank Faulty ISC solenoid valve control system Maladjusted idie speed adjusting screw Faulty air valve Faulty EGR system Fuel pressure out of specification Faulty injector Diagnostic flow chart B 5 See p 44 78 See p 4A
42. round R G wire open R G wire shorted to Lg wire or ground or poor A16 connec tion If all above are OK substitute a known good ECM and recheck NO Faulty REGTS Fig 4A 78 Diagnostic Flow Chart For Code No 51 2 California spec model only 4A 56 CODE NO 53 GROUND CIRCUIT FOR CALIFORNIA SPEC MODEL ONLY CIRCUIT OPEN ECM ECM coupler 3 Engine ground for ECM No Fig 44 79 Ground Circuit California spec model only 1 Disconnect ECM coupler from ECM with ignition switch OFF 2 Is there continuity between ECM cou pler terminal A4 and body ground B G wire open or poor engine ground Poor A4 connection If connection is OK intermittent trouble or faulty ECM Recheck referring to Intermit tent trouble on p 4A 31 1 ECM coupler disconnected 2 Body ground Fig 4A 80 Diagnostic Flow Chart For Code No 53 California spec model only 4A 57 CODE NO 54 5TH SWITCH CIRCUIT A5 TERMINAL GROUNDED 5TH SWITCH ON CONSTANTLY NOT FOR CALIFORNIA SPEC MODEL ECM ECM coupler 5th switch Sth switch coupler PWN Fig 44 81 5th Switch Circuit Not for California spec model 1 ECM coupler disconnected 2 Body ground Check 5th switch referring to p 4A 96 Is it in good condition Faulty 5th switch 1 With ignition switch OFF disconnect ECM coupler and 5th switch coupler respectively
43. s low that is when the air fuel ratio is smaller than the theoretical air fuel ratio fuel is richer electromotive force of the oxygen sensor increases and a rich signal is sent to ECM 2 Upon receipt of the rich signal ECM decreases the amount of fuel injection which causes oxygen con centration in the exhaust gas to increase and electromotive force of the oxygen sensor to decrease Then a lean signal is sent to ECM 3 As ECM increases the amount of fuel injection according to the lean signal oxygen concentration in the exhaust gas decreases and the situation is back to above 1 This contro process however will not take place under any of the following conditions At engine start and when fuel injection is increased after engine start When engine cooling water temperature is low When highly loaded and fuel injection is increased At fuel cut When oxygen sensor is cold Signal to decrease amount of fuel injection Signal to increse amount of fuel injection High voltage Low voltage a A F mixture Oxygen i becomes concentration richer decreases A F mixture Oxygen becomes cancentration leaner increases ECM Injector Oxygen sensor Voltage signal Injection signat Aic fuel mixture Exhaust gas Fig 4A 29 Fuel Feed Back Compensation 4A 24 ISC SOLENOID VALVE CONTROL SYSTEM This system controls the bypass air flow by means of ECM and SC solenoid valve for the following three purpo
44. ses To keep the engine idle speed as specified at all times The engine idle speed can vary due to follow ing reasons Load applied to engine when electric load is applied air conditioner is turned ON etc Variation in atmospheric pressure Change in engine itself with passage of time Other factors causing idle speed to change e To improve starting performance of engine To compensate air fuel mixture ratio when decelerating Dash pot effect Operation ISC solenoid valve opens the bypass air passage when it is turned ON by ECM and closes it when turned OFF ECM detects the engine condition by using signals from various sensors and switches and while repeating ON and OFF cycle of ISC solenoid valve at a certain rate 12 5 times a second it controls bypass air flow by increasing and de creasing its ON time within a cycle While the engine is cranking ECM keeps ISC solenoid valve ON maximum ON time rate within one cycle so as to obtain better start of the engine When the accelerator pedal is depressed while the engine is running the idle switch is OFF and the throttle valve is at other than idle position ECM sets the ON time of the ISC solenoid valve rate of ON time within one cycle so that it is determined by the engine conditions and keeps it When decelerating on the other hand ECM reduces the valve ON time gradually i e the bypass air flow is reduced gradually to obtain dash pot effect
45. switch OFF 2 With ignition switch ON is voltage applied to Gr R wire terminal of PS coupler about 4 5V 1 PS coupler 2 Engine ground Gr R wire shorted to power NOTE circuit If wire is OK substitute a known good ECM and re check Check PS referring to p 44 90 Is it in good condition ble that PS is also faulty Gr R wire shorted to Gr G wire Gr Y wire open poor A24 connection Gr G wire open poor A22 connection or poor PS coupler connection If wires and connections are OK inter mittent trouble or faulty ECM Recheck referring to Intermittent trouble on p 4A 31 Faulty PS Fig 4A 65 Diagnostic Flow Chart For Code No 31 When battery voltage is appli ed to Gr R wire it is possi 4A a9 CODE NO 32 PS PRESSURE SENSOR CIRCUIT SIGNAL VOLTAGE LOW LOW PRESSURE HIGH VACUUM ECM ECM coupler PS PS coupler To TPS To other sensors 1 2 3 4 5 6 Fig 4A 66 PS Circuit 1 Disconnect PS coupler with ignition switch OFF 2 With ignition switch ON is voltage applied to Gr R wire terminal of PS coupler about 4 5V 1 PS coupler 2 Engine ground YES NO Check PS referring to p 44 96 Gr R wire open Gr R wire shorted to Is it in good condition ground circuit or poor A23 connection If wire and connection are OK substitute a known good ECM and recheck YES

Download Pdf Manuals

image

Related Search

Related Contents

取扱説明書(PDF)  Simulation of the Rigid Body (Human Figure)  ECP200 EXPERT  Clique para fazer o do manual técnico do produto  User Manual  Energie: l`or noir tiré du bois Arboristes  HP Stream Notebook PC (model numbers 11-d000 through 11  1 - トヨタ自動車  ArWest AW435 User Manual  Memup Twist'n Key  

Copyright © All rights reserved.
Failed to retrieve file