So I recently got a 2002 Jeep Wrangler. It was cranking and but not firing when I first got it. I replaced the camshaft position sensor and the crankshaft position sensor and now it fires and runs good. I bought a new battery for it cause the old one was shot. I had a check engine light so I had a mechanic plug it in and he got (P1682 charging system voltage too low, P0463 fuel level sending unit bolts too high and P1495 Leak detection pump solenoid circuit) so he told me to replace the alternator and fuel sending unit. So I got a whole new fuel pump instead of messing with it and the pump works fine but still nothing on the fuel gauge. Replaced the alternator and the volt meter is still reading around 12 on the dash and I had just trickle charged the battery all night because the alternator wasn't charging the new battery at all. After I replaced the alternator I put a multimeter on the battery when the engine was off and it read 12.7, and when I turned the jeep on it read 12.66. So basically at this point nothing that I am trying to fix is working. I cleaned off all grounds I could fine and replaced the battery terminals. and still nothing. A mechanic told me that he plugged in another PCM that he had laying around when he was trying to get it to fire and it ruined that PCM. From what I have read on other forums I may have a bad voltage regulator which is in the PCM? How would I check that? If I were to outsource and install an external voltage regulator would it get rid of the check engine light? Or could there be a short somewhere and how would I check? Thanks for any help!
New battery and alternator, still no charge and ruined a PCM
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Look on the firewall where the engine harness goes across . Pull the harness away from the firewall and see if anything has been rubbing on it. I had a stud rub through the harness covering , wear through a wire, and wreck a pcm. Cut out the bad section of wire and soldered back together.
You could also check the harness with a pin out list. You basically find both ends on the list, check the wire with an ohm meter, and move on to the next one. That takes a while, but sometimes that's what it takes to find wiring issues.
Paul
You could also check the harness with a pin out list. You basically find both ends on the list, check the wire with an ohm meter, and move on to the next one. That takes a while, but sometimes that's what it takes to find wiring issues.
Paul
Thanks Paul,
I can’t seem to find anywhere that it is rubbing. I have continuity from the two field wires coming out of the alternator all the way to the PCM. I’m starting to think that there’s definitely some kind of short on the wiring for the PCM that is causing it to not communicate with the alternator to tell it to charge.
I can’t seem to find anywhere that it is rubbing. I have continuity from the two field wires coming out of the alternator all the way to the PCM. I’m starting to think that there’s definitely some kind of short on the wiring for the PCM that is causing it to not communicate with the alternator to tell it to charge.
If a wire gets shorted it can damage the pcm. The no charging issue would point to the pcm. But finding what is damaging the pcm could be difficult. You may have to take each connector on all the sensors and check them back to the pcm connectors.
My problem was one of the 4 IAC wires was pinched and grounding out on that stud on the firewall I was talking about. I fixed the wire, but it had already messed up the pcm, so I got ahold of another one and it was fine.
I would guess there is a pinched or damaged wire somewhere in the engine harness, it's just going to be hard to find.
Good luck
My problem was one of the 4 IAC wires was pinched and grounding out on that stud on the firewall I was talking about. I fixed the wire, but it had already messed up the pcm, so I got ahold of another one and it was fine.
I would guess there is a pinched or damaged wire somewhere in the engine harness, it's just going to be hard to find.
Good luck
Is the mechanics extra pcm doing the same thing (not charge)?Or did something else go bad on his?
Paul
Paul
Did a little digging. Found an older thread on another forum that has info. Sounds like if you ground the dark green wire and the alt starts charging, pcm is bad (from the other forum thread, I have never done it). There is a way to convert to an external voltage regulator but I have not done it myself (from the other forum thread also). Sounds like a good alternator and starter shop can do it easily. @Jerry Bransford may be able to shed a little light on this also. He was in the other forum post I found this info in.
Paul
Paul
That's a good question, I'm not sure. I will have to try and do some more digging on the previous work.
So I’ve made some progress. Cut the two field wires coming out of the alternator and grounded one and put power to the other and it made the alternator start charging. I just ordered an external voltage regulator so I’m thinking it’s going to at least make the alternator charge. Not sure if it’s going to help with check engine light or not.
Keep us updated.
I am not sure what sets the check engine code...it might not matter how the alt is getting its signal to charge. The pcm just might be monitoring voltage.
When I was looking for reman pcm for my TJ, I called a few different remanufacturers. The most common failure that they recieved was just bad solder joints . From what I understand, they would just re-solder and flash the pcm with the latest update for your vehicle.
I have seen a few videos of people fixing their own pcms. My soldering skills are not good enough for that tedious stuff.
Paul
I am not sure what sets the check engine code...it might not matter how the alt is getting its signal to charge. The pcm just might be monitoring voltage.
When I was looking for reman pcm for my TJ, I called a few different remanufacturers. The most common failure that they recieved was just bad solder joints . From what I understand, they would just re-solder and flash the pcm with the latest update for your vehicle.
I have seen a few videos of people fixing their own pcms. My soldering skills are not good enough for that tedious stuff.
Paul
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