Voltage seems high.

How well is the VR case grounded? Some have run a wire back to battery (-) to make sure.

Also reports of faulty external regulators exist.

How is the alternator/engine ground?

The previous owner spliced mine at some point, and the thing was green under the ancient electrical tape.

 

VR case is double grounded. Bolted into the firewall, and i have a line running from the vr case to the alt case. I moved this line from the alt to a ground in the engine compartment though.

I read somewhere to check volts from the alt case to ground... it should be zero or else you have a short. Mine came up negative volts with the positive on the alt case and negative on body metal. Positive lead on body metal and negative on alt case i'm reading a ton of volts... jumping all around up to 100. definitely not zero.

I thought the alt itself was grounded through its mounts? Seems like my alt isn't grounded properly.

 

It is high and is usually the result of the ground connection between the engine block and the body not being very good.

 

sorry for being thick but where does the block ground to the body? i checked the batt to block strap, but figured the block grounded through the mounts.

Also, are the mounting bolts on the alt harness also grounds, or are they just molded into the rubber case?

 

The alternator has 4 terminals, two field terminals, (+) and (-)

If the alternator was properly grounded through the mounting bolts, they would not have provided a (-) stud.


I believe many Dodges have no frame to engine ground from the factory. They just have one to the engine block from battery, and one to firewall behind battery.

Since the body's are welded to the frame rails, this is ok on a newer vehicle but after 20 years the resistance grows.

The firewall ground, is pretty thin metal too.

I have a 4 awg cable from my frame rail to my alt(-) stud.

I have another cable from my alt(-) stud to my engine block. From this same location on my engine block I have a ground right to the battery(-) This is foolproof grounding, and I do not need to look behind my air pump to see the battery to engine ground.

Make sure your battery cables are in good condition, and the mating surfaces of the terminal lugs and battery studs are gleaming like polished silver.

 

my alternator does not have 4 terminals, it has three. two field coils, and B+.

it looks like this:


except it has two mounts, one on either side of the field terminal. either way, i ran a ground wire from the alt case to the VR case bolted to the firewall.

my batt terminals are shining and my cables are in good condition.

 

Hmm, mine has a similar looking plug, but two fat wires exiting it. The one bolt hole closest to the connector is the ground on mine, but the alternator is a different model too. Perhaps they thought the ground was redundant in '90 or the alternator was designed to be grounded through the case. Minecase is grounded but there is a seperate ground.

I would try another voltage regulator, new means nothing, and monitor voltage in different conditions and make sure the battery does not get too low in the mean time. Be extra careful with sparks if 15.1v+ stays common

 

Ok, so the voltage I was picking up off the alternator body was just my meter switching to milivolts without me knowing... I bought a digital for this job and was used to analog, didn't realize they did this. doh!

Can't find a short or a bad link anywhere... I ordered a transpo adjustable regulator and i'm going to install it and see if I can just adjust the voltage down to the proper range.

I think autozone just sold me the wrong regulator. They insisted my car had one because it showed up on their computer, even though I know my 1990 doesn't have one.. I got them to give me on as a freebie because of the alternator thing.

I should have known autozone was useless... i called NAPA to ask about the adjustable regulator and to compare them to the zone, and they knew my model had no regulator and suggested an adjustable one for my fix before i asked for one.

Autozone sucks, I really feel like they ripped me off for $140 by false testing my alt.

 

I've had my issues with autozone too. I don't give them my business or waste my time there anymore, though I do recycle my oil there

 

It would seem that way on the surface, but keep one thing in mind. An alternator can work perfect when cool and not work after heating up. When AZ tests the alternator it has had sufficient time to cool.