1993 Jeep Other

Electrical problem
1993 Other Jeep Models V8 Four Wheel Drive Automatic 174k miles

My 93 jeep grand cherokee has a charging issue. When the vehicle is warm or it is warm outside the alternator charges at the very minimal of about 13-13.6 volts. When it is cold outside 40 degrees and lower it charges at over 14 volts. If you put the transmission in reverse the voltage gauge slowly drops and has dropped as low as 9 volts according to the gauge. It will come back up some in reverse depending on how many rpms the engine is running (at idle it drops). If the blower motor is on high at idle the voltage drops, but if it is on the setting below high or any other position the voltage stays the same. If the wipers are on continuously at idle the voltage drops, but is fine if the vehicle is moving. If the blower motor is on high, wipers on, and or the headlights are on too the voltage gauge drops and will go down to the red. Often times if I have the interior lights on I can see them pulsate and watch the voltage gauge needle pulsate also, while at idle. The left turn signal blinks very slowly and causes the voltage gauge to drop at idle. The right turn signal flashes normally and doesn't affect the voltage gauge at idle. The left turn signal always flashes slow, but does increase it's speed depending on how cold it is. The alternator is new and checks out good. The battery is new, fully charged, and tests good. Now corrosion on the battery terminals or cables. I haven't found any wiring breaks or issues, although the left turn signal bulb was burned out and bulb socket was scorched. I replaced the bulb and the signal works, but just doesn't blink as fast as it sould. My door locks won't lock, but will open and my overhead console works intermittently. I think the locks and console are caused by the chime module, as I don't have any warning light for seat belt or any chime or buzz for seatbelts or any other warning light. Unfortunately I haven't been able to get to the chime module to look at it yet. The jeep charges ok as long as the engine rpm's are above idle, although it may not always be charging at what appears to be around or slightly over 14 volts according to the voltage gauge reading. My fear is this is a BCM problem, as I know the alternators on these vehicles are computer controlled. Any suggestions of what the problem might be?
January 10, 2010.

Let me try to help here-The computer controls the field generation of the alternator-its like a built-in voltage regulator

Double check the battery and connections, also at the alternator wiring connector if all okay-check fuse no.8 and 16 60 amp, and also test the ASD relay also the PCM wiring connectors/connections

See the charging system EWD

Jan 11, 2010.
Sounds like good info. Hopefully I can troubleshoot this using the info. You provided later this weekend. I'll let you know how it turns out.



Jan 12, 2010.