Need electrical help over charging

slor1de

slor1de

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Joined
Feb 17, 2007
Messages
907
Looking for some input on my early 04. Truck is over charging, running around 17.7-14.8. Have put 2 new alt on it thinking faulty, new battery's. Truck is throwing 0108 map sensor voltage high, 0643 primary 5 volt supply circut high, 0642 sensor reference voltage 1 circut low. truck is also throwing 0480 fan control and 0483 fan speed, it has always thrown these 2, but never given me a problem. Also threw a govoner pressure sensor voltage too high but after clear'd has not came back. Any input greatly appreciated truck doesnt seem to run that great either. Thinking possibly pcm but don't have access to try one and can't afford to buy one and not fix the problem.
 
That's what I was afraid of. When u say ECM, not PCM that's mounted on driverside of engine?
 
The pcm functions are integrated into the ecm in 04, so it's all one module. Just a shot in the dark, but unplug the fan clutch and try it. I've seen those things do some funky chit
 
slor1de said:
That's what I was afraid of. When u say ECM, not PCM that's mounted on driverside of engine?
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Yes and Yes. I have a few good used ecms but you'll need the vin reset so your truck runs, which I may possibly be able to handle as well.

However you go, I would like your old ecm. ;)
 
I have a buddy with another early 04 auto same as mine. I'll try the PCM from it and see what happens
 
My friend was dealing with the same crap on his 04. During the process of trouble shooting and ohming wires we had to remove the ecm plugs. Removed the plugs from the ecm and reinstalled, problem fixed. Corrosion or moisture will cause some strange issues. Factory service manual has a very good trouble shooting guide for over charging conditions.

Tapamaxxing
 
LReiff said:
Yes and Yes. I have a few good used ecms but you'll need the vin reset so your truck runs, which I may possibly be able to handle as well.

However you go, I would like your old ecm. ;)
Click to expand...

I've never reset the vin on any ECM swaps. I've always done manual to manual and auto to auto. 03-05 trucks. Havnt tried on 06-07 tho.
 
So if you reset the vin can you put an auto ECM on a manual if you have the right harness or vise versa?
 
chris lang said:
So if you reset the vin can you put an auto ECM on a manual if you have the right harness or vise versa?
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I have done a few auto to manual swaps and have used a smarty and a bully dog to make the ECM manual friendly. So I would assume so. No need for harness change if your just swapping ECM's tho.
 
Just my $.02 but clean your battery cables. I had the same issue last Summer, passenger side battery boiling over, truck throwing fan clutch, and ECM codes. Cables looked clean but even a little corrosion can make these things do some weird chit. The crossover cable on the radiator support is always a good place to start.
Good luck.
 
as suggested before check the plugs for your ECM's and PCM's. contact cleaner and blow it dry. you are over charging because there is unwanted resistance (corrosion) on the sensing circuit to your alternator. EASIEST wires to check first are the signal wires from the alt back. on my 05 they mount them in a funny position and it can get dirty there. if that checks out i would do the plugs for sure. You can trow money at it thinking its an ECM, but they are pretty robust, internally clean and sealed, and rarely fail. Also as a side note, check EACH ECM/PCM ground cable. make sure it has a good clean ground. If the controller can reference right because of a bad ground it will do all kinds of funny things. Hope this helps you out.
 
Anything specific to look for in another PCM or as long as its out of an early 04 auto like mine.
 
PCM is body mounted, ECM is engine mounted. Which do you need? As others have said, you most likely have a ground issue. We just fixed an 05 with the same issue, had a bad ground circuit in the engine harness.
 
You're truck may be, not all are. Never the less, the engine mounted control module on a Cummins is always called an ECM.
 
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I would do a resistance check on your ground wire coming from the battery, than move along on the circuit from there checking each ground along the way that is involved in your problem. That is most likely your issue.
 
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