Module 3 PGMFI Flash Type Diagnostic Trouble Codes
Contents
1. most common one used and is still used heav ily in current Honda models 3 2 1 OBD II Exceptions With the more sophisticated and powerful OBD II monitoring systems being used since 1996 more elaborate strategies are being used Beginning with OBD II in puts are now checked for rationality and signal behavior in addition to just being checked against a high low value OBD II systems typically require that a malfunction occur on multiple consecu tive trips before a DTC is stored and the MIL is illuminated Also on OBD II sys tems the DTC will stay in memory and the car will not use the input until the car has completed 40 trips without a malfunction 3 3 MIL Light When a malfunction is sensed the ECM will illuminate the MIL and store a DTC The car will ignore the input for the remainder of the trip and substitute informa tion to the ECM from an internal table When the car is recranked the ECM will attempt to use the input again If the input is still malfunctioning the ECM will again ignore the input illuminate the MIL and use a built in default value The MIL had several different looks over the years It has been labeled PGMFI Check Engine and Check inside a logo of an engine Beginning in the late 1980s and early 1990s some Honda models could also set automatic transmission DTCs The automatic transmission DTCs used the S S3 and D4 as the MIL This training module only covers PGMFI DTCs not automatic transm2. the ECM has a pre programmed strategy that is implemented The strategy could be as simple as substituting a fixed pa All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_ 002 Page 3 8 Visit Our Website www tech2tech net rameter for the malfunctioning input Some strategies could be rather complex and have an effect on other input parameters and or disable monitor testing used on OBD II equipped cars This is a very common mistake made by many seasoned Honda techs Many techs have gotten into the habit of clearing DTCs only after a repair has been made Running diagnostics with stored DTCs on later model Hondas could cost you dearly in diagnostic time do not do it There are several ways to clear the DTCs 3 7 1 Disconnecting Power to the Car You can always disconnect power to the entire car by disconnecting the battery This is not the best way to reset DTCs since it also will require you to re program the radio and other accessories If the radio is an anti theft radio you will be re quired to enter the password to get it working again On OBD II equipped cars it will also erase adaptive learning that is stored in the ECM memory 3 7 2 Pulling the ECM Memory Fuse You can clear the ECM memory by disconnecting power pull a fuse to the ECM for at least 10 seconds This technique will not affect the radio preset stations or cause the radio to lock up till the security code is re ente
3. CS also makes all DTCS set illuminate MIL on the first malfunction even though their normal strategy may require as many as three malfunctions to set This makes the diagnostic process easier and faster Obviously with the scan tool plugged up you will not be able to jump pins 4 and 9 from the face of the 16 pin OBD II DLC To jump the SCS with a scan tool plugged up to the OBD II DLC jump the wires brown and black in the harness behind the DLC It is easy to pop the DLC out of its holder and get to the wires on the back side of the 16 pin connector Actually the black wire is ground so you could even simplify this by simply jumping the brown wire to chassis ground Another easy way to do this is to just clamp both wires with one bed of nails type clip This procedure is shown in Image 3 4 The table in Section 3 8 identifies the models that are directly read at the ECU The table in Section 3 9 identifies which ones are read at the dashboard MIL after the service connector is shorted 3 5 Reading DTCs 3 5 1 OBD I Systems When a malfunction is sensed on an input circuit the ECM will ignore the spe cific input and resort back to a preset internal value When this happens it will also light the MIL and store a DTC to indicate which input has failed The input will be ignored until the car is restarted and the ECU will attempt to use the input again If a malfunction is sensed it will Image 3 5 ECM PCM LED Readouts repeat the proces
4. Module 3 PGMFI Flash Type Diagnostic Trouble Codes Author E mail URL Grant Swaim sureseal nr infi net www tech2tech net IMPORTANT READ Do not read or study this information unless you agree to the following conditions The information in this training module is the intellectual property of N Grant Swaim and is copyrighted by Sure Seal Phone 336 632 9882 Products Inc Fax 336 632 9688 Subscribers to the Tech 2 Tech website and persons partici i pating in Tech 2 Tech s on line training program are entitled to read this material on line Postal Address Tech 2 Tech Website PO Box 18443 You may also click on the save icon on the Acrobat viewer Greensboro NC 27419 and save a copy to your local computer You may save a copy of this file on one computer and it must be viewed from 2 that ter Physical Address 220 4 Swing Rd BT ee Cape Greensboro NC 27409 You may also print one copy of this file for your viewing If the printed copy becomes illegible or lost an additional copy may be printed Last Update April 2000 Tech 2 Tech offers the following training modules in printed manual CD ROM and on line formats PGMFI Training Modules OBD II Training Modules e The PGMFI System Overview Part 1 e On Board Diagnostics General Overview e The PGMFI System Overview Part 2 e Diagnostic Trouble Codes e PGMFI Flash Type DTCs e MIL Freeze Frame e Inputs Outputs Part 1 e Sc
5. PGMFI DTCs you may find DTCs for automatic transmission controls SRS air bags anti lock brakes etc This training module focuses on the PGMFI DTCs The standard Honda flashed DTCs are readable without using any special tools These DTCs are read by counting the number of flashes either at the engine con trol module ECM or at the dashboard MIL The Honda self diagnosing system has evolved over the years The first Honda PGMFI system in 1985 used only 11 DTCs By the 1998 model year over 45 dif ferent flashed DTCs have been used All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_ 002 Page 3 2 Visit Our Website www tech2tech net 3 2 DTC Strategies The majority of the DTCs represent a specific input signal When the ECM senses a problem with an input it will illuminate the MIL and store a DTC in memory for later retrieval The conditions that trigger a DTC are referred to as a strategy The exact strategy that is required to set every DTC is not typically covered in service manuals The design engineers establish the strategies and the ECMs are pro grammed accordingly While knowing the exact strategy used by the ECM for each input is not crucial it can help when diagnosing the systems The earlier systems used very basic strategies such as a high low signal value strategy If the input signal was above or below a specific level a DTC was set The high low signal strategy is the
6. When multiple DTCs are experienced you need to let it go through the sequence several times to make sure you read them all and read them correctly 3 6 Using This Information While Diagnosing The ability of the Honda PGMFI system to self diagnose itself and store DTCs for later retrieval is indeed the good news part When there is a failure that sets a DTC the diagnosing process is usually much faster and easier The bad news is that often problems are present without setting a DTC The situation that happens all too often is that techs get lazy and assume there is no problem since a DTC has not been set In the real world many problems with noticeable symptoms can occur and never set a DTC The strategies used to set a DTC prior to 1996 non OBD II models were fairly conservative and used little or no logic Most of the strategies were based on simple high low limit strategies and the input parameter had to be almost an open or a short to set a DTC For an example here are two real world problems that do not usually set a DTC 3 6 1 Defective Engine Coolant Temperature ECT Sensor The ECT sensor on a Honda PGMFI system has been known to fail without setting a code The strat a BBL egy established to set a code on the ECT sensor in put voltage appears to be a simple high low voltage strategy The high and low trigger voltage appears to be a very conservative and wide range I have substituted the ECT sensor with a variable resis
7. an Tool e Inputs Outputs Part 2 e Scan Tool Advanced e Engine Control Module e Monitor Tests Overview e Air Flow MAP Sensor Base Inj Pulse Width e Comprehensive Component Monitor e Fuel Delivery System e Catalyst Monitor e Closed Loop Strategies Theory e EGR Monitor e Closed Loop Strategies Case Studies e Evaporative Monitor e Thermistor Inputs e Fuel System Monitor e Throttle Position Sensor e Misfire Monitor e EGR Valve Lift Sensor e Oxygen Sensor Monitor e MAP BARO Sensor e Oxygen Sensor Heater Monitor e Ignition Inputs e P Codes e Vehicle Speed Sensor e Oxygen Sensor e Lean Air Fuel Sensor e Miscellaneous Input Signals e Fuel Injectors Miulti Port Injection e Fuel Injectors Dual Point Injection e Ignition System Outputs e Idle Air Control Valve 2000 All Rights Reserved Sure Seal Products Inc Greensboro NC Miscellaneous Training Material e Glossary of Terms Visit Our Website www tech2tech net Page 3 1 3 PGMFI Flash Type DTCs 3 1 General Overview All Honda PGMFI systems are equipped with a self diagnosing feature The sys tem will light a malfunction indicator light MIL and store a diagnostic trouble code DTC in memory when a malfunction is sensed in an input signal and out put signals on OBD II equipped Hondas Honda actually uses two different types of DTCs the scan tool retrievable P codes and the MIL flashing type In this training series we will focus on th
8. e flashing DTCs The Honda PGMFI system has maintained a diagnostic trouble code DTC re porting system from the first systems to present This DTC reporting system is in addition to the scan tool retrievable DTCs This reporting system was the only way to retrieve PGMFI diagnostic information until an engine control module ECM data link connector DLC was added The first DLCs 3 pin type were added to 92 Civics Preludes and 1994 Accords This was a proprietary protocol and was not OBD II compliant It allowed a tech to retrieve DTCs with a scan tool in addition to reading flash DTCs A scan tool could also be used to read a freeze frame FF and view some live parameters from this DLC In 1996 1995 V 6 Accords a 16 pin OBD II DLC was added that was even more powerful OBD II equipped Hondas offer a set of industry standard OBD II DTCs in addition to Honda s flashed DTCs The OBD II DTCs can be retrieved using any OBD II compliant scan tool The Honda OEM scan tool will retrieve more data parameters than a generic scan tool The OBD II DTC reporting system is more detailed than Honda s flash DTC sys tem Most input signals have only one flash DTC yet may have as many as three OBD II DTCs assigned to it The expanded OBD II DTC set will typically indi cate information such as a high reading a low reading or an inconsistent reading from all the sensors The newest Hondas have many different DTCs available In addition to the
9. ission DTCs 3 3 1 OBD II Exceptions Beginning with OBD II equipped Hondas the MIL command status ON OFF can be read from a scan tool If the ECM has commanded the MIL to be on it will All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_002 Visit Our Website www tech2tech net Page 3 3 be listed in the all parameters list on your scan tool This is a good check to make sure that the MIL light bulb or MIL circuit has not been disabled On OBD II equipped models some DTCs will not set and illuminate the MIL unless a malfunction occurs on multiple consecutive trips Some DTCs require a malfunction to occur on up to 3 consecutive trips before the MIL is illuminated The MIL is not extinguished on an OBD II car until the car is driven on three consecutive trips without the malfunction occurring again 3 4 Retrieving DTCs 3 4 1 Read at ECM In the earlier systems the DTCs were Image 3 1 3 Pin DLC Location read directly at the ECM When the MIL was lit you would turn the key to run and read the codes by counting the flashes from a light emitting diode LED on the ECM There are two dif ferent styles of direct read LED systems The two different styles are covered in detail in the Reading DTCs section 3 4 2 Read at MIL 2 Pin Service Check Connector SCS On later systems a 2 pin service check connector SCS is jumpered and the codes are flashed on the dashboard MIL I
10. mage 3 1 shows the 2 pin SCS marked by white arrow This connector is typi cally located behind the dash at the lower right corner Image 3 2 Service Check Connector Note that there is another connector right beside the 2 pin SCS a 3 pin con necter This is a data link connector DLC and is used by a scan tool to re trieve serial data from the ECM It is easy to confuse this connector for the SCS The DLC is a 3 pin connector but sometimes only has two wires in the connector Always jump the wires that are in the connecter with only 2 cavities All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_002 Page 3 4 Visit Our Website www tech2tech net All the 2 pin SCSs can be jumpered by using a wire and the later systems have a SCS tool available from Honda The Honda SCS tool that works on all late model systems is part O7PAZ 0010100 and retails for 3 75 shown in Image 3 2 3 4 3 Read at MIL SCS Located in OBD II Connector Image 3 3 SCS 16 Pin Jump Pins T Ot neal Ht le F dl On the 1998 and up Accords the SCS was moved from a separate 2 pin con nector to the 16 pin OBD II DLC SAE only defines a few of the 16 pins and the manufacturers in any way they would like can use the remaining pins In this case Honda chose to use two of them as a SCS To short the SCS you need to jump pins 4 and 9 as shown in Image 3 3 That will be the 4 pin from the to
11. p left cor ner when looking at the mating face of the DLC and the wide part of the con nector is at the top and the 1 pin on the bottom left corner when looking at the mating face of the DLC and the wide part of the connector is at the top You can always check the wire colors on the backside of the DLC jump the brown and black wires Image 3 4 Jumping SCS The 1998 Honda Accord service manual actually lists a special SCS jumper for this application however it was never produced Honda recommends shorting the SCS connector with the Honda OEM scan tool Manually shorting this connector works fine Now is where it gets interesting You can indeed jump the SCS with the OEM scan tool You navigate to the proper place in the scan tool menu and jump the SCS by picking Jump SCS The only problem is when you leave this area to do anything else with the scan tool you loose the SCS jumpered condition As the Honda OEM scan tool is programmed at present you cannot jumper the SCS and use the tool for any other useful purpose at the same time All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_002 Visit Our Website www tech2tech net Page 3 5 It is important to be able to jump the SCS and use the scan tool for diagnostics at the same time As you will see in the OBD II section jumpering the SCS does more than just allow you to properly set the ignition timing Jumpering the S
12. red It will however loose any adaptive learning that is stored in the ECM memory 3 7 3 Clearing Codes with a Scan Tool Screen Capture 3 2 The absolute best way to clear DTCs from a Honda is to use a scan tool By using a scan tool you can CLEAR MENU reset just the DTCs and not reset the adaptive learn PGM FI 1 DTC DATA CLEAR ing or clear the entire ECM 2 ECM RESET Screen Capture 3 2 shows this menu from the Honda OEM scan tool Choice 1 will clear all DTCs and reset the OBD II monitors to incomplete This leaves adaptive learning unchanged Choice 2 will do all that choice 1 does plus clear adaptive learning same effect as pulling the ECM fuse All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_ 002 Visit Our Website www tech2tech net Page 3 9 3 8 DTCs Read From The ECM Table 5 6 3 9 DTCs Read From The Flashing MIL Table Read these DTCs from the flashing MIL after shorting the 2 pin service connector 9 Accord At right bottom edge of dash Accord Integral with the OBD II DLC short the brown and black wire together ivic At right bottom edge of dash RV At right of center console near dash Six Sfo Ala oo e Ko oc co Q O N O oo 3 10 Honda Flash DTCs Table The following chart lists all flashed DTCs in use by Honda from 1985 1998 If the MIL is lit and there is no code present the MIL does no
13. s The DTC that was stored in the ECM memory will be re tained indefinitely as long as power to the ECU is maintained The DTCs can be retrieved and read at a later time Of the direct read at the ECU systems there are two different styles of LEDs The earliest systems used a series of 4 LEDs in a row that were numbered 8 4 2 and 1 You simply add up the numbers on the lit LEDs to get the DTC shown on top ECM in Image 3 5 The genera tion after the 4 LED systems uses a sin gle LED that blinks You count the blinks of the single LED to determine All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_002 Page 3 6 Visit Our Website www tech2tech net the DTC shown on the bottom ECM in Image 3 5 The single blinking light whether read at the ECU or on the dash board MIL has two different styles On the earlier systems all blinks stood for a 1 You simply count the number of blinks to determine the DTC Each DTC is separated by a 3 second pause When the DTCs became numerically large it became impractical to display only 1 s The later systems use a long blink and a short blink The long blinks count as 10 and the short blinks count as 1 For example 3 long blinks and 1 short blink stands for a 31 DTC The earlier systems only store one DTC at a time The later systems can store multiple DTCs The multiple DTCs are displayed sequentially with a pause be tween each DTC
14. t come on at all comes on dimly or flickers the ECM might be bad Oxygen Sensor A Primary Defective circuit or unplugged defective sensor Oxygen Sensor B Defective circuit or unplugged All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_002 Page 3 10 Visit Our Website www tech2tech net po defective sensor O MAP Sensor Manifold Absolute Defective circuit or unplugged CKP Sensor Crankshaft Position Defective circuit or unplugged MAP Sensor Manifold Absolute ECT Sensor Engine Coolant Tem Defective circuit or unplugged TP Sensor Throttle Position Defective circuit or unplugged ec cea Ere TDC Sensor Top Dead Center Defective circuit or unplugged ee eee ee CYP Sensor Cylinder Defective circuit or unplugged BE ae IAT Sensor Intake Air Tempera Defective circuit or unplugged BARO Sensor Atmospheric Pres Defective circuit or unplugged sure defective sensor IAC Valve Idle Air Control Defective circuit or unplugged defective sensor defective fuel injector defective sensor Control Solenoid Valve defective solenoid valve BE e eee defective sensor ee E oi Valve defective solenoid valve EGR Lift Sensor Exhaust Gas Re Defective circuit or unplugged circulation defective sensor E Ignition Output Signal Missing or defective ignition output signal VTEC Oil Pressure Switch defective oil pressure switch defective sensor A
15. they also check for signal rationality and will typically catch these types of problems 3 6 2 Camshaft Timing Set Incorrectly The Manifold Absolute Pressure MAP Sensor has a major effect on the base in jector PW The MAP sensor is monitoring engine vacuum and is effectively a load detector for the PGMFI system When a drop in manifold vacuum is present indicating a load the ECM will increase the PW If the camshaft timing is off even by one tooth the manifold vacuum drops and the PW is widened in anticipation of the load the ECM thinks the engine is ex periencing The car can be sitting in your shop idling and the ECM simply thinks that the car is climbing Pikes Peak Again if the strategy is based on a simple high low input voltage range test this malfunction would go unnoticed A slightly more sophisticated strategy could recognize that the low manifold pressure should not be present when the throttle is closed and the vehicle is sitting still Rationality testing used on OBD II vehi cles will typically recognize this problem and set a code When a DTC is set due to an irrational relationship between two or more inputs the descriptor of the DTC will end in as expected For example this scenario would probably set the DTC P1128 Manifold Absolute Pressure Lower Than Expected 3 7 Clearing DTCs As soon as a stored DTC is recorded it should be cleared before any diagnostics are performed When a DTC is stored
16. tor and ran Hondas on ranges from 250 ohms to 20 000 ohms without a DTC setting The ECT sensor has to almost go to an open or a short to set a DTC Screen Capture 3 1 1 TIME 3 LUL 4 GHD 5 t4 6 TRIG F HOLD MEHIJ An ECT sensor will commonly fail by sending a All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_ 002 Visit Our Website www tech2tech net Page 3 7 cold coolant signal to the ECM after the car is warmed up as shown in Screen Capture 3 1 This really causes problems if the car is cut off and recranked hot The cold signal from the defective ECT sensor at start up will cause the ECM to drive the PW as wide as 60ms or more This rich condition will typically flood a hot Honda causing it to not start For a more detailed explanation of this situation read Chapter 11 Thermistor Inputs A simple high low voltage limit will not catch this problem as long as the ECT sensor values stay within the acceptable range The ECT sensor shown in Screen Capture 3 1 did not set a DTC even with the voltage jumping between 6v and 4 25volts Obviously this is a situation that is physically impossible The engine coolant cannot go from 200 degrees to 0 degrees and back to 200 degrees in a matter of seconds With a more sophisticated strategy this situation could be caught and have the ECM store an ECT DTC The strategies used with the OBD II equipped Hondas are more advanced
17. utomatic Transmission Signal B defective sensor Primary Oxygen Sensor Heater Circuit malfunction Fuel Supply System Defective or malfunctioning fuel supply system All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_002 Visit Our Website www tech2tech net Page 3 11 ee ea ee systems LAF Sensor Lean Air Fuel defective sensor Ea ee Fluctuation fective sensor ee eee fective sensor er eee Primary response es Secondary response 65 Oxygen Sensor Heater Secondary Malfunctioning or defective oxygen sensor heater Catalyst system Efficiency Below Threshold lyst system transmission controls Misfire ing a cylinder misfire Misfire ing a cylinder misfire Misfire ing a cylinder misfire 74 Cylinder 4 Misfire or a Random A condition is present that is creat Misfire ing a cylinder misfire Misfire ing a cylinder misfire A condition is present that is creat Misfire ing a cylinder misfire 80 Exhaust Gas Recirculation Insufficient flow detected ECT Sensor Engine Coolant Tem Circuit range performance prob perature lem ea Evaporative Emission Control Sys Leak detected in the fuel tank area tem 941 Fuel Tank Pressure Sensor Low input ES Evaporative Emission Control Sys Insufficient purge flow tem All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_ 002
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