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The PCM monitors critical inputs to control fuel injection, ignition, emission and other engine management functions. The PCM has also been programmed to monitor several charging system related circuits.
Battery Feed To PCM
Alternator Field Control
Battery Charging Voltage (High And Low)
If a problem is sensed in a monitored circuit, a fault code is stored in the PCM's memory and the CHECK ENGINE light will be turned on (with a few exceptions). Fault codes can be read using the CHECK ENGINE light or with the Chrysler Diagnostic Readout Box-II (DRB-II).
NOTE:Fault codes remain in memory for 50 engine starts. Fault is erased from memory if failure does not reoccur.
For certain fault codes, CHECK ENGINE light will illuminate and PCM will enter limp-in mode. In limp-in mode, PCM attempts to compensate for particular component failure by substituting information from other sources. This allows vehicle operation until proper repairs are made.
UNSTEADY OR LOW CHARGING
Check for loose alternator belt, defective alternator, and/or charging resistance too high. High resistance could be caused by loose alternator or engine ground wire, and/or corroded battery terminals.
NOTE:Only charging system-related codes are listed here. For engine-related codes, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
CHECK ENGINE Light Diagnostic Mode
Start engine (if possible). Move transmission shift lever through all positions, ending in Park. Turn A/C switch on and then off (if equipped).
Turn engine off. Without starting engine again, turn ignition on, off, on, off and on. CHECK ENGINE light will come on for 2 seconds as a bulb check, followed by fault codes. Record 2-digit fault codes as displayed by flashing CHECK ENGINE light.
For example, Code 23 is displayed as flash, flash, 4 second pause, then flash, flash, flash. After a slightly longer pause, any other codes stored are displayed in numerical order.
Once check engine light begins to flash fault codes, it cannot be stopped. Code 55 indicates end of fault code display. Go to step 1) to enter diagnostic mode again. For more information on vehicle self-diagnostics, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
Refer to CHARGING SYSTEM FAULT CODES table to translate trouble fault code number to a circuit description (same description is displayed in DRB-II display). Once trouble area is identified, refer to appropriate charging system tests under TESTING (ON-VEHICLE) .
CHARGING SYSTEM FAULT CODES
Fault Code/Circuit Description/CHECK ENGINE Light On
12...........Battery Feed To PCM..............No
41 (1)..... Alternator Field Control...........Yes
44 (1) (2).. Battery Temp. Sensor..........Yes
46 (1)...... High Battery Voltage.............Yes
47 (1)....... Low Battery Voltage............Yes
55............End Of Diagnostic Mode.........No
(1)This code will cause limp-in mode.
(2)Sensor is inside PCM. If faulty, replace PCM.
Friday, March 6th, 2009 AT 7:56 PM