Manager Forum

Hello everyone.
I have a 2000 Jeep Grand Cherokee limited,4.0 4x4.. towed in last week. jeep started running bad (chugging/missing and raw fuel smell from exhausts.)
Looked at jeep and seen ( check gauge light on,abs light on,air bag light on, brake light on and digital mileage reader flashing.) . The source of the check gauges light was no voltage reading.. Ran a battery tests ok, checked alt no voltage.. Ok changed alt figure the no amperage or voltage causing ECM and BCM to go crazy....Installed new altenator assy .Still no voltage reading at gauge but this alternator is charging (has output.) No codes for running condition present...

Only info in computer system is (stored energy firing / loss of ignition / run/start....no cluster messages......) Also code 32 controller failure, code 37 system over voltage.....

Can both PCM and BCM be bad or just PCM.......???????????????

Inspected all connections and computer connections no corrosion or broken wires.......Did come across blower motor connector unplugged.. plugged it in and blower comes on...with all fan and hvac knobs shut off and no key in the ignition...( suspect that to be a faulty blower motor resistor...)

Anyone seen this issue before??????

Thank you..

Both could be bad if there was a serious over voltage. PCM controls alt field. On a side note the PCM is programmed to vehicle so I wouldn't recommend used, could cause more problems. I personally would run the test for the charging system in Mitchell. One other thing...these codes should be P codes. Haven't seen a Chrysler output 2 digit codes since 95 or 96. What type of scanner are you using?

Using a Solus pro.. NO p codes anywhere.... Yes I agree only reman pcm is all we use...

Thats odd no P codes. Are you able to pull the vin from the PCM?

Just double checked .. NO p codes set. Ran through system again with scanner the two number codes are in the antilock brake section...NO VIN # that I could find..

Ok so you can communicate with the PCM. I would look to see what the desired charge rate is and what the field command is. Scope the field at the alternator to see if it matches the PCM command. There is a test in Mitchell, under Chassis, Anti-Lock, for the ABS overvoltage. See where that leads ya.

We work on a lot of Jeeps and I've only seen one where he P.C.M. failed effecting the charging system. I have seen my fair share of broken wires and bad power distribution boards. When checking power to distributer also look at amps. This is critical. It may be a P.C.M. since one of the codes is a system over charge The P.C.M. could have shorted, forced spike and then shut down. Usually this type of short trashes the module and it can't be re built. Not being able to pull the vin is another indicator. The spike may have blown the dash and the Power Control Module also. I would look into the distribution box board before I went anywhere else. Almost sounds like it may have been effected by a lightning strike.

Changed out PCM....Car works fine and everything back to normal... Pcm has a lot of corrosion around it, suspect water damage....Thanks everyone for your advise.....

Congrats, thanks for posting the fix.