Charging problems

little6cylinder

little6cylinder

Everything is "fixable"
Joined
Mar 7, 2011
Messages
1,218
On my 97 I had an exhaust leak off the hp turbo. It melted a small spot on the wiring harness and it fell down and grounded out on the hot pipe:doh:. I pulled the harness apart and replaced the spot where it melted only 1 wire. I have since relocated the ECM to the driver side, and fixed the exhaust leak.

When this happened my tach, and speedometer stopped working. It blew a fuel pump fuse(I believe, going off memory) on the fuse panel inside the cab, and fried my alternator. I replaced the fuse, checked all the other fuses and replaced the alternator. Now everything works, but the truck still wont charge. I don't have a wiring schematic or this would be a lot easier. Anyone have any quick ideas? Maybe the reman alternator they gave me is junk? :nail:
 
I'm guessing you meant you moved the PCM since a '97 doesn't have an ECM.

Did you check the 140amp alternator fuse?
 
Yea the PCM sorry. Alternator fuse is good. I do have power at the alternator as well.
 
BigPapa said:
Are you saying you have 12V to one of the little studs with the 8mm nuts? I think it's the top one, correct? The lower one should be grounded.
Click to expand...

I obviously have power at the big power out from the alternator. The top small stud is ignition power. And the lower is not grounded(on mine atleast) the ground is a bigger one on the side.
 
The way I understand it, with the truck running, if the PCM is calling for the alternator to charge, the top small stud should have 12V going to it and the lower small stud should be grounded. The PCM controls the ground causing the alternator to charge.

If I am wrong, someone please correct me.

I have run a small jumper from the positive battery terminal to the top small stud to force the alternator to charge when I had a wiring issue. If this doesn't cause the alternator to charge, I'd say you have a bad alternator. If it does cause it to charge, you have a PCM, wiring, or sensor issue.
 
You possibly could have burnt the regulator up that is inside the PCM so the alternator isn't being told to charge.
 
little6cylinder said:
I don't have a wiring schematic or this would be a lot easier.
Click to expand...

charging.jpg
 
Thanks, I'm going to work on it tomorrow. Hopefully get it figured out. I'll post what I find out.
 
Sounds like you may of fired your voltage regulator, do you have anything at all for an output? And it is possible that the new alternator is junk had it happen a few times before
 
Last edited:
Well it fried the PCM. Right now, until I do a one wire alternator I just have the PCM controlled ground hooked up to a switch. At idle it charges at 14.6 volts but if I leave the switch flipped it will overcharge above 1700 rpm. Thanks for the help.
 
Just buy a external regulator for a older 80s Dodge. That What I used for my pulling truck with no ecm/pcm on it.

from phone
 
It's already done. Did it last night. The generator light comes on though because the PCM doesn't know what's happening. So I got rid of it. It charges perfect though.

Thanks for the help guys. I didn't want to buy a new PCM.
 
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