mixamatchi

Pardon me, if there is a thread elsewhere. I have not found what I'm looking for with a search. Feel free to direct me to the correct thread.

I bought a 2000 Grand Cherokee 4.0l/2wd for my daughter's first vehicle. It's in pretty good shape, and has only 151k on it. I have been driving it to shake it down, and find any gremlins that I do not wish my 16yr old to deal with. So, the first real problem has appeared. I left my home and went to the end of the block, and noticed all of the gauges died, all of the warning lights are on, and the truck died. It restarted immediately, and I drove back home. After significant searching, I found a good guide for troubleshooting the problem. I found that the bus voltage is supposed to be .5-2.5 volts (max 7.0), fluctuating with data. Upon testing, I observed with key on/engine off, my bus voltage is correct. After starting the engine, the bus voltage immediately increases to 9.9-10v. Truck seems to run fine. I have driven it short distances as it is. I have tested it disconnecting the stereo, the door controls, the airbag computer, the skis anti theft and the clockspring, yet the high bus voltage persists. I am hesitant to change the PCM, as the truck runs good, and I have seen many posts where the PCM was changed and the problem persisted. If anybody has any useful advice, I would greatly appreciate it.

Prior to this problem, the airbag light was on, and has been on since I bought the truck. I have probably put 300mi or so on it, before this problem occurred.

Ramcharger93

Had a problem with my registration/lost password/etc. Created a new profile. Hoping to solve this problem. So, Ramcharger93 is also the OP, Mixamatchi.

I have been trying to determine the source of the high voltage on the PCI bus in my 2000GC. It is still as described above, but the voltage seems to be a little higher now at as much as 11.45vdc. Again, it is only present when the engine is running. It leads me to believe it is the PCM, but if it is, I am confused that the engine seems to run perfectly. I have tried disconnecting the radio, ac head, SKIM module, clockspring, air bag controller, both front door panels, and the overhead console. The high voltage still persists. Any more suggestions are welcome.

I am not opposed to replacing the PCM, but I am not sure I have isolated the problem. I would hate to replace the PCM, only to find it isn't the problem.

Ramcharger93

Well, nobody seems to have any suggestions, but I'll keep posting until I get this resolved. Maybe it will help the next guy.

So far, I have removed the above items temporarily for testing. Still persistent high bus voltage. I have since removed the cluster as well. Still no joy. It was also suggested to me that the o2 sensors wiring could be shorted and caused this. I have tested with each, and both sensors removed. No change. Wiring looks ok. I have found the fuse/relay/junction panel under the left side of the dash. I removed the harnesses, and reinstalled them. I also reoriented them a little, to take stress off of the wiring. Still no luck. I may swap this box out for a junkyard item. I have read there is a module behind the glove box. Gonna try that next.

It has also been suggested to me that I find the point where all the data lines come together, and test from there. It was referred to as a bus bar of sorts. It is supposed to be at the base of the steering column, but I have yet to find anything resembling that.

For those who are keeping score, bus voltage is normal with key on/engine off.
Bus voltage rises to as much as 11.45vdc about 1 second after the engine starts.
While the engine is running, and bus voltage is high, voltage at the battery reads 14.0vdc.