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When the engine is started, the check engine light should illuminate for 3 seconds as a bulb test. If the light illuminates at any other time, a fault has been detected. Not all fault codes are stored in memory.
The dealer can read fault codes with the DRB series diagnostic tool.
98+ Rams do not flash the codes, but on 94-97 Rams, the owner can read the codes this way:
If any problem is repaired or ceases to exist, the fault code stored
in the PCM will be erased after 51 engine starts. All stored codes will
be erased if the battery is disconnected for 15 minutes, but a fault code
12 will be set when the battery is reconnected..
||Code Description. Service hints.|
||No Distributor reference signal detected during engine cranking. Check the circuit between the distributor and PCM.|
||Direct Battery input to PCM disconnected within last 50 ignition key-on cycles. Normal if battery has been disconnected, otherwise check battery power and ground connections.|
||No difference seen between the engine MAP reading and the barometric (atmospheric) pressure reading at startup. Indicates a problem with the MAP sensor vacuum system.|
||MAP sensor voltage output is outside the acceptable range.|
||No signal received from the vehicle speed sensor during road load operation.|
||Engine temperature too high or too low while traveling. Check coolant level, radiator cap, temperature sensor, and thermostat.|
||O2 sensor does not detect rich or lean condition, or O2 sensor input voltage too high. DRB will indicate which side with dual sensors. The O2 sensor signal should fluctuate under normal conditions.|
||Engine Coolant temperature sensor input out of normal range. Check engine temperature sensor.|
||Intake air manifold temperature sensor is out of range. Check sensor.|
||TPS sensor is out of normal range.|
||A short is detected in one or more of the idle air motor circuits.|
||Injector number # output driver circuit does not respond to the control signal. Check the affected circuit.|
||Short or open in the EVAP solenoid circuit. Check for loose, broken, or shorted wire in the charcoal canister purge solenoid wiring and connectors.|
||Short or open in the EGR solenoid circuit. Check for loose, broken, or shorted wire in the EGR valve wiring and connectors. Possible air fuel ratio imbalance not detected during diagnosis.|
||Short or open in the AC clutch circuit.|
||An open or short in the speed control vacuum or vent circuits. Speed control switch input above or below normal range.|
||Open or short in the radiator fan relay wiring.|
||Open or short in CKT wiring or connectors. Voltage out of range at transmission temperature sensor input. See NOTE #1 below|
||Open or short in the generator (alternator) field control (regulator) circuit. This indicates a problem with the charging circuit and the fault is set when the battery voltage from the ASD relay falls below 11.75 volts. Wiring, connectors, fuses, and the ASD relay should be checked. A shorted battery cell can also trigger this fault.|
||Open or short in the ASD relay wiring or connectors.|
||Open or short in number # coil circuit. Indicates that the ignition coil's peak primary circuit current is not achieved with the maximum dwell time.|
||An open or short in the engine coolant temperature sensor circuit or a problem in the PCM's battery temperature circuit.|
||Transmission OD solenoid circuit failure. Open or short in the transmission overdrive solenoid circuit.|
||Battery voltage sense input above target charging voltage during engine operation. Computer is indicating that the battery voltage is not being regulated.|
||Battery voltage sense input above target charging voltage during engine operation. Also, no significant change in battery voltage was detected during a test of the generator output.|
||O2 sensor signal indicates lean air/fuel ratio during engine operation. The computer ran the mixture to the rich limit of programming, but the O2 sensor still indicated a lean condition. L or R indicate left or right side O2 sensor. Fuel pressure problems can lean the mixture and set this fault.|
||O2 sensor signal indicates rich air/fuel ratio during engine operation. The computer ran the mixture to the lean limit of programming, but the O2 sensor still indicated a rich condition. L or R indicate left or right side O2 sensor. Faulty ignition components, high or low fuel pressure, or leaking injectors can set this fault.|
||An internal PCM failure or PCM communications failure has been detected.|
||No fuel sync (camshaft signal) detected during engine crank. No camshaft position sensor signal was received from the distributor. Problem with the distributor synchronization circuit.|
||End of message code. A DTC 55 is used to end all DTC messages. This code does not show on the DRB tool and indicates a completion of the stored codes on the Malfunction Indicator Lamp (check engine lamp).|
||Unsuccessful attempt to update Service Reminder Indicator miles in the PCM EEPROM (memory).|
||Unsuccessful attempt to write and EEPROM location by the PCM. Controller failure, check the PCM. This code can be set when attempting an unauthorized reprogram of the PCM.|
||The auxiliary 5 volt supply output voltage is low. The 5 volt output signal is not reaching the required voltage level.|
||The catalytic converter is not converting emissions in the proper ratio.|
Fault codes with * = Check engine lamp may not illuminate at all times if this code was recorded.
Fault codes with ** = Check engine lamp will illuminate when the engine is running if this code was recorded.
Fault codes with red stars * or ** vary from above, depending on the model year.
NOTE #1 - From the 1995 TRUCK (Ram) manuals: the trailer towing package includes a transmission coolant temp sensor while the standard package doesn't. The fault code detection system is probably the same for both models. This could cause the low (no) voltage indication....no sensor to send any voltage.
Other Lists of Chrysler Computer (PCM) Fault Codes
Last Update: April 14, 1999