SUPPLEMENTAL RESTRAINT SYSTEM(SRS)
Contents
1. Low rating capacity Function of the energy reserve switch If there is fault in the energy reserve system warning lamp will turn on And defects are found by continuous checking of the condenser voltage the system will enter overall shutdown status for safety reason Shutdown Switch There is 1 energy shutdown switch in the system and it will be checked during start up And it also checks that condenser is discharging properly If shutdown switch is short it will be detected during condensor voltage test If squib line fault is obvious the warning lamp will turn on and the module will enter overall shutdown status Accelerometer Check Accelerometer function will be checked during start up During operation accelerometer off set signal will be checked If there is fault module will enter overall shutdown status ASIC Overheat Module monitors upper side ASIC overheats continuously If overheated the module will enter overall shutdown status Microprocessor Fault Module checks EEPROM ROM checksum and RAM during start up EEPROM tests checksum operation If RAM or ROM checksum is defective module will not allow start up continuously but will be re set If EEPROM is defective warning lamp will turn on and the module will enter overall shutdown status During operation RAM will continuously verify the proper operation of temporary memory program data usage If there is fault the module will enter overall shutdown status and2. 4 Air bag control unit internal defects X e Check and replace the ECU 1 2 3 4 5 07 10 11 12 13 14 15 16 8B 12 SUPPLEMENTAL RESTRAINT SYSTEM SRS Squib No Squib No Squib No Squib No Squib No Squib No 2 resistance 3 resistance 4 resistance 1 resistance 2 resistance 3 resistance Driver s squib resistance is higher than standard 4 5 0 5W Check related circuits for open short Check connection of connector Check the ECU Replace the squib wire Plus side short 7k ground side short 6kW Driver s squib resistance is higher than standard 4 5 0 5W Check related circuits for open short Check connection of connector Check the ECU Replace the squib wire Plus side short 7k ground side short 6kW Driver s squib resistance is higher than standard 4 5 0 5W Check related circuits for open short Check connection of connector Check the ECU Replace the squib wire Plus side short 7k ground side short 6kW Driver s squib resistance is higher than standard 4 5 0 5W Check related circuits for open short Check connection of connector Check the ECU Replace the squib wire Plus side short 7k ground side short 6kW Driver s squib resistance is lower than standard 1 4 0 3W Check related circuits for open short Check connection of connector Check the ECU Replace the squib wire Plus side sh
3. 1 cycle of blinking will be repeated every 5 seconds Blinking Code 1 Sec 0 05 1 15 2 25 3 35 4 45 Blinking Code 3 J LJ LI LO LL Sec 0 05 1 15 2 25 3 35 4 45 8B 10 SUPPLEMENTAL RESTRAINT SYSTEM SRS SELF DIAGNOSIS 1 Position the ignition switch to OFF 2 Connect the harness connector of scanner to the diagnosis socket in engine compartment 3 Turn the ignition switch to ON position 4 Select Electronic control vehicle diagnosis from function selection display and press Enter 5 Select Musso 98 model year from vehicle model selection display and press Enter 6 Select Electronic air bag from control system selection display and press Enter 7 Select Self diagnosis from diagnosis item selection display Notice Check sensor value of output display if necessary 8 Determine the fault code and trace defective component Notice Refer to self diagnosis list SUPPLEMENTAL RESTRAINT SYSTEM SRS 8B 11 Self Diagnosis List Fault Appli Code cation Driver s squib side No 1 e Short of side No 1 in the driver s squib circuit e Check connection of connector e Check the ECU Driver s squib side No 2 e Short of side No 2 in the driver s squib circuit e Check connection of connector e Check the ECU Driver s squib side No 3 e Short of side No 3 in the driver s squib circuit e Check connection of co
4. When the ignition key is turned to ON position SRS warning lamp will turn on for 6 sec and go off In this case the system is normal For the following cases see service manual SRS warning lamp does not turn on SRS warning lamp does not go off SRS warning lamp continues to blink C Steering Wheel Body Inner Warning Before removing the steering wheel read service manual first Set the front wheels straight forward and align the center position marks of SRS clock spring Improper removal or installation of the steering wheel can damage the SRS components Replace the air bag module and air bag unit with new if it dropped cracked or damaged Only qualified technicians in service shop should check or repair the air bag Before service should be well noticed of warning labels on the vehicle D Engine Compartment Warning This vehicle is equipped with air bag Before checking the engine compartment read service manual first Faultuy check and service can cause SRS air bag deployment and system defects that can be led to severe damage E Battery Cable Warning Before disconnecting the battery power read service manual first 8B 4 SUPPLEMENTAL RESTRAINT SVSTEM SRS FUNCTION DESCRIPTION Air Bag Control Unit AC4 Air bag control unit AC4 is installed on the center portion of the front floor tunnel Itis a central control unit that control all functions and determines whether deploy
5. bag control unit internal defects capacity e Check and replace the ECU Energy reserve No 2 current off e Air bag control unit internal defects capacity e Check and replace the ECU Energy reserve No 3 current off e Air bag control unit internal defects capacity e Check and replace the ECU Energy reserve No 4 current off e Air bag control unit internal defects capacity e Check and replace the ECU Energy reserve No 5 current off e Air bag control unit internal defects capacity e Check and replace the ECU Condensor voltage e Air bag control unit internal defects e Check and replace the ECU Collision times checksum e Air bag control unit internal defects e Check and replace the ECU Driver s acceleration sensor e Air bag control unit internal defects e Check and replace the ECU Driver s acceleration sensor off set e Air bag control unit internal defects e Check and replace the ECU Arming sensor e Air bag control unit internal defects e Check and replace the ECU 41 Major USA Air bag control unit internal defects e Check and replace the ECU 2 NM EN 6 2 3 31 3 3 3 3 6 E 5 7 7 3 3 3 2 28 9 0 2 3 4 5 8 9 0 4 8B 14 SUPPLEMENTAL RESTRAINT SYSTEM SRS Over heat e Air bag control unit internal defects e Check and replace the ECU SENS e Air bag control unit internal defects e Check and replace the ECU Standard band gap e Air bag control unit internal defec
6. before starting service Notice Though battery cable is disconnected air bag control unit will maintain backup power for 150ms and air bag can be inflated so wait for min 30 seconds 2 Remove the console box and center fascia panel assembly 3 Remove the heater control switch and audio assembly 4 Remove the lower side panel of the driver s portion and glove box 5 Remove the lower main panel 6 Release the lock lever of the AC4 connector and disconnect the connector 7 Unscrew 3 nuts and remove the AC4 Notice For installation horizontal position should be secured for the better changes of collision pulse between the vehicle body and air bag control unit 8 Installation should follow the removal procedure in the reverse order Inspection Procedure 1 Check AC4 case and welt bolts for crack or deformation 2 Check connector lock lever and terminal for deformation Notice Replace the AC4 with new if dust deformation or corrosion found 8B 22 SUPPLEMENTAL RESTRAINT SYSTEM SRS GENERAL DESCRIPTION AND SYSTEM OPERATION INTRODUCTION SRS Supplemental Restraint System air bag protects driver and passenger by inflating air bag under collision and seat belt pre tensioner is a supplemental equipment for seat belt reducing shocks from the collision by pulling passenger s body against seat back at the same time of air bag inflation Air bag unit has diagnosis functions and indicates system m
7. SECTION 8B SUPPLEMENTAL RESTRAINT SVSTEM SRS Caution Disconnect the negative batterv cable before removing or installing anv electrical unit or when a tool or equipment could easilv come in contact with exposed electrical terminals Disconnecting this cable will help prevent personal injurv and damage to the vehicle The ignition mustalso be in LOCK unless otherwise TABLE OF CONTENTS noted Specifications c x x e e e vee iw wan 8B 1 General Specifications 8B 1 Schematic and Routing Diagrams 8B 2 AIRBAG a a a 8B 2 Caulis cnc sie bie T RT e 8B 3 Function Description 8B 4 Air Bag Module 8B 6 DIAg OSIS i ones vedere wae KE K KR semet 8B 7 Description 8B 7 Self DIagnosis i 8B 10 Circuit Diagram LL 8B 16 Air Bag Diagram css x a 9 0 d d 0 d 0 S S T 5 8B 17 Maintenance and Repair 8B 18 On Vehicle Service 00 8B 18 Air Bag Module 8B 18 Clock Spring 8B 19 Air Bag Control Unit AC4 8B 21 General Description and Svstem Operation 655 98 9 0 R 9 RR 6 R 6 doce sade 8B 22 Introduction 8B 22 Caulonia iii 8B 22 SPECIFICATIONS GENERAL SPECIFICATIONS Application Air bag System Deployment Time Detection Time Operating Temperature Storage Temperature Air Bag Replacement Interval Voltage Range Current Consumption Acceleration Range Max Acceleration Voltage Ramp Energy Reservation Inflator Ignition Energy Squib Res
8. Shorting Bar 26 Shorting Bar 27 N A 28 Shorting Bar 29 Shorting Bar 30 NA 8B 6 SUPPLEMENTAL RESTRAINT SYSTEM SRS AIR BAG MODULE Air bag module is installed in the pad of steering wheel center and inflator is consisted of igniter explosives gas generating material and bag When crashed the air bag control unit sends current to the air bag module through squib line and this current ignites as ignition energy 6mJ momentarily igniting explosives and bag will be inflated by nitrogen gas protecting driver at the same and then deflates 1 Air bag Module 5 Retainer Ring 2 Module Housing 6 Inflator 3 Bag 7 Horn Switch 4 8 Module Bracket Backing Plate SUPPLEMENTAL RESTRAINT SYSTEM SRS 8B 7 DIAGNOSIS DESCRIPTION Air bag control unit continuously controls system function as follows during ignition ON or driving Recognition of collision Internal diagnosis External diagnosis If recognize or detect defects warning lamp will turn on If there is danger of improper deployment the system will enter overall shutdown status and the air bag will not inflate Air bag control unit will store detected internal and external defects in the EEPROM System Control Battery Voltage Check Battery voltage will be monitored continuously If voltage is out of normal operating range all system diagnosis will stop and warning lamp turn on Bator votage Y System diagnosis stops and warning lamp turns on Normal operation range S
9. alfunctions to the driver by turning on the air bag warning lamp CAUTION Perform the service procedures for the air bag system as ordered if not the air bag can be operated suddenly and it could result in damage of air bag or injury Before service removal installation checking and replacement of parts observe the following instructions and service correctly 1 To service turn the ignition switch to LOCK position and disconnect the negative battery cable and continue the procedures after approx 30 seconds 2 If the vehicle is damaged due to accident remove the air bag ECU first to get the accident records 3 Never use the other vehicle s air bag parts and replace with genuine part if required 4 Do not disassemble or repair the air bag module air bag unit and wiring harness to reuse 5 Replace the air bag unit or air bag module if dropped cracked or damaged
10. can not be repaired e Do not disassemble or modify e To adjust to the center position rotate clockwise until it stops and then rotate it counterclockwise 2 3 0 2 revolutions and align marks If not airbag system can not work normally and driver can be injured seriously 8B 20 SUPPLEMENTAL RESTRAINT SYSTEM SRS Removal amp Installation Procedure preceding work removal of steering wheel 1 Turn the ignition switch to OFF position and disconnect the battery negative cable Start the procedure after waiting over 30seconds 2 Unscrew 3 screws from lower cover on steering column shaft and remove the lower cover 3 Unscrew 4 screws from clock spring and remove the clock spring Installation Notice e Don t try to repair and modify the clock spring e When aligning the neutral position turn to clockwise until it stops and turn to counter clockwise until the marks are aligned SUPPLEMENTAL RESTRAINT SYSTEM SRS 8B 21 AIR BAG CONTROL UNIT AC4 Removal amp Installation Procedure AC4 is installed on the center portion of the front floor tunnel Built in accelerometer sensor detects collision and determines action or non action and ignition time Notice Do not disassemble the AC4 to repair If defective replace it AC4 should not be shocked or vibrated by dropping on the ground or bumping Replace the AC4 with new after air bag inflation 1 Disconnect the negative battery cable and wait for 30 seconds
11. internal defects e Check and replace the ECU Fault Code gt ke 42 43 44 45 46 4 4 9 50 51 52 53 54 55 56 57 58 59 60 SUPPLEMENTAL RESTRAINT SYSTEM SRS 8B 15 Fault Appli L A 127 Collision signal e Air bag control unit internal defects e Check and replace the ECU 128 Collision number e Air bag control unit internal defects e Check and replace the ECU 8B 16 SUPPLEMENTAL RESTRAINT SYSTEM SRS CIRCUIT DIAGRAM CLOCK SPRING TO A BAG CPU yo DRIVER amp A C INFLATER L REMOCON CONTROL SWITCH HORN SWITCH SUPPLEMENTAL RESTRAINT SYSTEM SRS 8B 17 AIR BAG DIAGRAM 8B 18 SUPPLEMENTAL RESTRAINT SVSTEM SRS MAINTENANCE AND REPAIR ON VEHICLE SERVICE AIR BAG MODULE Removal amp Installation Procedure 1 Remove the steering wheel rid LH RH with a screwdriver Installation Notice Each position mark LH RH is stamped on the inner surface of the rids 2 Unscrew the bolts from both sides Installation Notice Tightening Torque 7 11 Nm 3 Disconnect the connectors and remove the air bag module 4 Installation should follow the removal procedure in the reverse order SUPPLEMENTAL RESTRAINT SYSTEM SRS 8B 19 CLOCK SPRING General Specification Current Rating Air Bag Circuit Resistance 0 16 0 380 40 85T isolating Resistance Rotating Range 2 7 3 1 Rotation from neutral Position to Both Sides Notice e Clock spring
12. istance Air Bag Warning Lamp ON Time When Ignition ON 5ms after ignition switch ON lt 1A 8B 2 SUPPLEMENTAL RESTRAINT SYSTEM SRS SCHEMATIC AND ROUTING DIAGRAMS DIAGNOSIS PIN 10 E I o UC O Q OD na L LU I LU co a UD jA kl AIR BAG SHORTIN BAR zo HO fo KOR fo a l Peo jo dk 3 ABS ALT C FAN Q BoA j AT SUPPLEMENTAL RESTRAINT SYSTEM SRS 8B 3 CAUTIONS Failure to follow the correct service procedure can cause air bag damage or personal injury due to unexpected air bag deployment Before service removal and installation of part check for replacement please be weal noticed of following items for your correct service 1 For service turn the ignition switch to LOCK position and wait for 30 seconds after disconnecting the negative battery cable If the vehicle collapsed remove the air bag ECU first to reserve the crash records Never use other vehicles air bag components and replace with specified new part Never disassemble or repair the air bag module air bag unit and wiring harness to re use A Sun Visor Side Warning Pull down the sun visor and see SRS air bag warning lamp on the head lining B Head Lining Warning 1 This vehicle is equipped with air bag Air bag is supplemental device for the seatbelt Fasten your seatbelt This air bag should be replaced by authorized supplier within replacement intervals
13. nnector e Check the ECU Driver s squib side No 4 e Short of side No 4 in the driver s squib circuit e Check connection of connector e Check the ECU 0 0 0 0 0 Driver s squib ground side No 1 e Short of ground side No 1 in the driver s squib circuit X X X e Check and replace the ECU X Driver s squib ground side No 2 e Short of ground side No 2 in the driver s squib circuit e Check and replace the ECU circuit e Check and replace the ECU Driver s squib ground side No 4 e Short of ground side No 4 in the driver s squib X circuit e Check and replace the ECU Driver s squib ground side No 3 e Short of ground side No 3 in the driver s squib X Energy shutdown switch No 1 Air bag control unit internal defects e Check and replace the ECU Energy shutdown switch No 2 Air bag control unit internal defects X e Check and replace the ECU Energy shutdown switch No 3 Air bag control unit internal defects e Check and replace the ECU Energy shutdown switch No 4 e Air bag control unit internal defects e Check and replace the ECU Ignition switch wire No 1 Air bag control unit internal defects e Check and replace the ECU Ignition switch wire No 2 Air bag control unit internal defects X e Check and replace the ECU Ignition switch wire No 3 Air bag control unit internal defects e Check and replace the ECU Ignition switch wire No
14. ort 7k ground side short 6kW Driver s squib resistance is lower than standard 1 4 0 3W Check related circuits for open short Check connection of connector Check the ECU Replace the squib wire Plus side short 7k ground side short 6kW Driver s squib resistance is lower than standard 1 4 0 3W Check related circuits for open short Check connection of connector Check the ECU Replace the squib wire Plus side short 7k ground side short 6kW SUPPLEMENTAL RESTRAINT SYSTEM SRS 8B 13 Fault Code M gt 25 57 Squib No 4 resistance e Driver s squib resistance is lower than standard 1 4 0 3W e Check related circuits for open short e Check connection of connector e Check the ECU e Replace the squib wire e Plus side short 7k ground side short 6kW Energy reserve No 1 voltage e Air bag control unit internal defects e Check and replace the ECU Energy reserve No 2 voltage e Air bag control unit internal defects e Check and replace the ECU Energy reserve No 3 voltage e Air bag control unit internal defects e Check and replace the ECU Energy reserve No 4 voltage e Air bag control unit internal defects e Check and replace the ECU Energy reserve No 5 voltage e Air bag control unit internal defects e Check and replace the ECU Energy reserve No 6 voltage e Air bag control unit internal defects e Check and replace the ECU Energy reserve No 1 current off e Air
15. the air bag or not with the collision signal from the built in accelerometer sensor and has function of diagnosing system defects Internal air bag control unit is consisted as follows e Microprocessor ASICs Upper side ASIC amp lower side ASIC Accelerometer sensor Arming sensor System energy backup condenser Squib energy backup condenser System energy Squib energy reserve reserve capasitor capasitor 1 Over voltage and reversed polarity Upper side ASIC protection System functions amp High side squib drivers Battery supply L Battery voltage j supervision Warning fa lamp a Accelerometer Configuration input Serial _ communication Lower side ASIC Arming sensor Low side squib drivers Input amp Output Function SUPPLEMENTAL RESTRAINT SYSTEM SRS 8B 5 Electronic air bag control and diagnosis module is connected by full 30 pin connectors Input ground Output 1 squib line warning lamp Input output communication diagnosis Connector Pins 15 30 0 ONDOUIS WIN Lamp Ground N A N A Ignition N A N A CONF N A N A N A N A Squib Line 1 upper Squib Line 1 lower N A Ground connection or open Air bag control unit Warning lamp Air bag lamp Communication diagnosis 13 RxD TxD 16 Shorting Bar 17 Shorting Bar 18 Shorting Bar 19 Shorting Bar 20 Diagnosis 21 Shorting Bar 22 Shorting Bar 23 NoPin 24 NoPin 25
16. the warning lamp will turn on Watchdog Test Watchdog function will be tested in start up If there is fault during the test warning lamp will turn on and the module will enter overall shutdown status SUPPLEMENTAL RESTRAINT SYSTEM SRS 8B 9 Diagnosis Air bag control unit diagnoses each function in the intervals of 250ms 20 sec during start up or driving to prevent unwanted air bag deployment If there is defect it turns on or blinks warning lamp to indicate defects in the air bag system to the driver And fatal defect is found air bag control unit enters overall or partial shutdown status and fault code will be stored Air bag control unit diagnoses following items Start up ignition ON Ignition TR Acceleration Microprocessor RAM and ROM Watchdog Shutdown Switch During Driving Squib resistance Squib line short to battery and ground Energy reserve system Lamp output Battery voltage ASIC communication Arming sensor ASIC overheating RAM and W D EEPROM Lamp Blinking Mode There are 2 kinds of blinking mode 1 When system internal fault is found the lamp will stay on 2 The lamp will blink according to external fault and there are 2 blinking codes Blinking code 1 Squib resistance fault in the driver s air bag squib line Blinking code 2 Squib short on plus and minus in the air bag squib line Lamp blinking code is as follows The last blinking will be within 0 5 sec and
17. ts e Check and replace the ECU Temperature sensor e Air bag control unit internal defects e Check and replace the ECU Warning lamp e Open short in the warning lamp circuit e Check related circuits for open short e Check connection of connector e Check the ECU Battery voltage e Power wire voltage is out of standard voltage 9 16V e Check the battery for voltage and charging e Check related circuits for open short e Check connection of connector e Check the ECU Fault code list e Air bag control unit internal defects e Check the ECU USA communication e Air bag control unit internal defects e Check and replace the ECU LSA communication e Air bag control unit internal defects e Check and replace the ECU No EEPROM program e Air bag control unit internal defects e Check and replace the ECU EEPROM checksum e Air bag control unit internal defects e Check and replace the ECU EEPROM map e Air bag control unit internal defects e Check and replace the ECU External watchdog 1 e Air bag control unit internal defects e Check and replace the ECU Arming sensor no close e Air bag control unit internal defects e Check and replace the ECU RAM check e Air bag control unit internal defects e Check and replace the ECU System e Air bag control unit internal defects e Check and replace the ECU External watchdog 2 e Air bag control unit internal defects e Check and replace the ECU Pulse e Air bag control unit
18. ystem diagnosis stops and warning lamp turns on Squib Diagnosis It checks not only high 4 50 5 or low 1 40 5 resistance but also short resistance 1 10k status between the battery and ground to indicate defects in squib line by blinking warning lamp Air bag control unit AC4 can measure squib resistance Warning Lamp Turning On Air bag control unit detects system defects during ignition ON or driving and displays following 2 warning lamps Warning lamp ON internal defects of the air bag control unit Warning lamp blinking higher resistance than standard in the squib line or short at the battery or ground Safety Function Check It checks defects during operation of the arming sensor If the sensor is shorted for more than 2 seconds the module will enter overall shutdown mode Temperature Sensor Function of the temperature sensor will be monitored continuously If there is fault due to defective sensor or short the lamp will turn on and program will take calibration temperature 25 of collision conditions Power Supply Airbag control unit operates in 9 16v and the characteristic of the system has backup condenser to supply the power for max 150ms if there is power defect during collision 8B 8 SUPPLEMENTAL RESTRAINT SYSTEM SRS Energy Reserve System Energy reserve system is consisted of condensor and energy switch and will check following items continuously during system operation High voltage Low voltage
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