Overcharging issue, 86 2.2 Turbo LeBaron

Last summer my wife and I scooped up an 86 LeBaron off an older lady for free. She had put I think 3 alternators in it in a few years and finally got fed up with it and replaced it with a mid 2010's TDI Passat. I noticed it had a mopar voltage regulator piggy back installed on the alternator when I scooped it up but it wasn't charging. I just drove it onto my tow dolly, and then drove it home. Ordered a new Chrysler style alternator last fall, and then finally got around to replacing it about 2 weeks ago. I removed the external voltage regulator, got the reman alternator in, fired it up, and confirmed it was charging around 13.7 volts just fine. Took it for a 20 minute trip, and halfway through it popped a power loss light. I did a small launch with it (and discovered it had a torn vacuum line because it hit boost cut) and the voltage surged to the top of the gauge on the dash. Pulled it back in the barn and cut it off.

I then disconnected the wires going to the ECU, and tried hooking up the external voltage regulator by itself, and it wouldn't charge at all. Fed it a 12V key on source to the field + wire, and it would instantly shoot up to 17V. I tried feeding it a source directly from the battery through a relay and get the same results. Bought a new external voltage regulator and had the same results. I did some research and thought it might be a bad ground so I added a large ground wire directly from the alternator to the voltage regulator case with no change in the results. Not sure what to do right now, Either thinking of putting on the old alternator to see if I can replicate this issue with it, or if it charges and I can return my new alternator to rockauto/ACDelco.

Here's the only photo I have for a reference of the alternator I'm dealing with, it is the alternator I removed.

https://i.imgur.com/GRY263I_d.webp?m...idelity=medium

Your Power Module computer is probably bad.

OK , I've done the external regulator in all my little mopars and my friends years past..

I know there's some screw-ie diagram out there showing the regulator with some "switched circuit"..yeah .. you DON'T need that

all you need is to connect the two field wires coming out of the alternator to the regulator and disconnect the ends going to the power module ..that's all you need to do

eliminate that switched circuit deal and you might be moving forwards..

a mechanic at the dodge store told me to simply connect the field wires to the external regulator .. it was twenty odd years later I saw the switched circuit thing ..here and thought .."you DON'T need that"

and if you cut the field wires at some point in front of the motor to connect to the ex- regulator you've already disconnected the P M in the process of redirecting the ends going to your new regulator

How to convert to an external voltage regulator . Here is a really good post from the knowledge center on hooking up an external regulator.

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Originally Posted by tryingbe

Your Power Module computer is probably bad.

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Thank you, I had assumed that which is why I'm trying to make the external voltage regulator work. It's not common, but not exactly rare for the same thing to happen in the neon community which I'm slightly more familiar with.

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Originally Posted by jamesmonty

How to convert to an external voltage regulator . Here is a really good post from the knowledge center on hooking up an external regulator.

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Thank you, I did find that when I started trouble shooting my problems. That's the basic diagram I followed, but I'm still having issues but I was thinking I may have not followed something correctly trying to rush it along.

I did noticed when I first started troubleshooting the alternator that the ground was a little loose. Thinking back, I'm afraid I may have fried the alternator internally. When I ohmed out the field wires on it, they were open completely with no resistance between them. I'm going to get a new alternator and voltage regulator this weekend and start all over.

EDIT: Just realized I have a bosch style alternator and not the Chrysler style. Would there be any advantage to swapping over to the Chrysler style unit? Or is it just a matter of wiring?

field wires ,either can go to either terminal on the regulator .. there's no left /right, no +/-, wrong/right

forget the 12v switched .. to what where ..you DON'T need it ..

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Originally Posted by Dr. Johny Dodge

field wires ,either can go to either terminal on the regulator .. there's no left /right, no +/-, wrong/right

forget the 12v switched .. to what where ..you DON'T need it ..

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Car is currently charging. Absolutely did need a 12v switched source to work. Maybe it’s the type of alternator? I have a Bosch style, possible the Chrysler style is self exciting? Who knows. I’m just glad it’s charging.

My brand new alternator’s field was fried, the power module was bad, and the voltage regulator was fried because the 12v switched source was wired to the wrong side.

it’s currently charging at 14.5V steady.

Congrats!!

Great work. That’s a lot of stuff to go wrong at once.

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Originally Posted by chromguy

Congrats!!

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Thanks!

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Originally Posted by cordes

Great work. That’s a lot of stuff to go wrong at once.

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Man you ain't wrong lol. Now I can move on to fixing the suspension and then hopefully get it registered.