GLH charging issue

[CoolV300C]

So I had a dead battery recently, and replaced it. Then out driving not long after the volt meter in the car started moving down, and the car finally lost all power and died. Replaced the alternator.

That was about two weeks ago (and less than 30 miles ago). Now driving tonight the volt meter was down near the red for a bit, but eventually went up to where it should be. When I drove home in the dark with the lights on, it dipped again, and kept dropping. Made it home barely, not even enough power left to light up the radio clock.

so the battery is new, and so is the alternator. Where do I start looking for the problem? It is a stock 85 GLH.

[thedon809]

Does it have a fuse link to the alternator?

[CoolV300C]

leading to it? Not sure, I'll have to check.

[Dr. Johny Dodge]

sounds like the voltage regulator is starting to fail

I'd doubt a little bit of fail here & there with a fuseable link - that should go like a bad light bulb

reg is built into the PM but an older style dodge regulator is an easy swap in with the correct pig tail to splice to the field wires

[turboshelbys]

I am betting on the field wires, 90% of the td's we have come in it's them. should be green. when you open one up there are only a couple of tiny chords in them. these break over time, 30years now. get yourself some good wire and run new ones all the way to the connecter. i bet this will fix your problem

[cordes]

Does it have a fuse link to the alternator?

I believe there is a big mamma jamma one built into that cable near the battery. I've had a bad cable from the alt to the battery before and that caused an issue just like the one in the OP.

I am betting on the field wires, 90% of the td's we have come in it's them. should be green. when you open one up there are only a couple of tiny chords in them. these break over time, 30years now. get yourself some good wire and run new ones all the way to the connecter. i bet this will fix your problem

Will you generally get a code for that? Something about the battery sense signal?

[supercrackerbox]

I'd have to look to see for the older ones, but the code for my '91 Daytona is 41. Had to chase that one down a couple times recently. Rebuilt the alternator, went through the cables very thoroughly, and finally ended up replacing the SBEC the other day. So far so good now.

For the GLH, I would start by inspecting all the wiring, and if they all check out, swap the power module.

[CoolV300C]

Ok, I'll take a stab at the wiring. Is the voltage regulator/power module something that's still available?

[ATaylorRacing]

I had an issue with Matchbox in that almost every time I took a long drive it would no longer charge. The voltage regulator would be replaced with the same issue...even 3 alternators later. At the beginning of racing season last year the SAME issue! Sometimes it would not charge, then drop the hood and it would! Ended up being the wires going to the regulator! I could bend them down or to either side and no charge, but when I pulled them upwards it would! I zip tied it up and had no problems for several months. Went to a O Rerilly and they had the plug in to it...spliced it into place of the old one and never an issue since! Hopefully it will be that easy.

[turboshelbys]

I believe there is a big mamma jamma one built into that cable near the battery. I've had a bad cable from the alt to the battery before and that caused an issue just like the one in the OP.



Will you generally get a code for that? Something about the battery sense signal?

I have never seen a code for that on the early cars(pre 87)

The field wires are the two small wires connected to your alternator. there is not a fuseable link to them back to the bulk connector. replace them and make sure you use solder do not use butt connectors or twist them together.

[turboshelbys]

Ok, I'll take a stab at the wiring. Is the voltage regulator/power module something that's still available?

power modules are still available, but can be finicky at best. I have seen new ones not work properly. start with the wiring, its the easiest and cheapest to fix. if running the 2 new field wires does not fix your problem i would consider wiring in and aftermarket voltage regulator. they are inexpensive and very easy to do.

remember that the less wires you move around on this car the better off you will be. after 30yrs and a ton of engine heat most the wiring is in pretty bad shape.

[CoolV300C]

I have never seen a code for that on the early cars(pre 87)

The field wires are the two small wires connected to your alternator. there is not a fuseable link to them back to the bulk connector. replace them and make sure you use solder do not use butt connectors or twist them together.

Thanks for that tip.

[cordes]

Does it have a fuse link to the alternator?

I am betting on the field wires, 90% of the td's we have come in it's them. should be green. when you open one up there are only a couple of tiny chords in them. these break over time, 30years now. get yourself some good wire and run new ones all the way to the connecter. i bet this will fix your problem

I have never seen a code for that on the early cars(pre 87)

The field wires are the two small wires connected to your alternator. there is not a fuseable link to them back to the bulk connector. replace them and make sure you use solder do not use butt connectors or twist them together.

Thanks for pointing this out. I should have been more clear. There is a fusible link in the power line coming off of the alternator to the B+ terminal if I'm not mistaken.

[turboshelbys]

Thanks for that tip.

no problemo. omni's are notorious for this. I am not sure why, but they seem to be the ones that have the most problems with these wires.

[turboshelbys]

Did you get it fixed?

[CoolV300C]

Haven't had time yet. Should later in the week.

[Force Fed Mopar]

What I ran into was a weak pin in the LM plug on the voltage sense wire.

[CoolV300C]

power modules are still available, but can be finicky at best. I have seen new ones not work properly. start with the wiring, its the easiest and cheapest to fix. if running the 2 new field wires does not fix your problem i would consider wiring in and aftermarket voltage regulator. they are inexpensive and very easy to do.

remember that the less wires you move around on this car the better off you will be. after 30yrs and a ton of engine heat most the wiring is in pretty bad shape.

so it wasn't the field wires, and it was starting to get beyond my repair skill level, so I took it to a nearby shop that I like, and the aftermarket regulator is what they suggested. I trust them, and the feedback here seems to suggest it is common. But what went bad in the original setup that makes an external one necessary? I guess I don't understand what this fix does.

[black86glhs]

The regulator is built in to the pm. The external one takes it's place when it goes bad and can't regulate the voltage.