Me too! It cannot be coincidence that removing fender paint behind the regulator reduced gauge movement from dancing to slight nervousness and then using a fatter ground cable from the regulator to the ground stud on the alternator eliminated the nervousness. That needle was pegged for better part of a week. Now it’s back to dancing. I do not get it.

Remember awhile back I reworked the two field wire connections to the alternator and that steadied the gauge needle too…for a week or two.

It makes me look like a fool when I keep saying it’s fixed only for it to unfix itself a week or two later.

Totally baffled! And why I hate electronics.

 

I was never a fan either, but, I was certified in automotive electronics, so, guess what I usually got stuck with?

From what I have been reading, it's a symptom of a bad connection somewhere. Trouble is, it could be anywhere. Considering how often you have gone thru things under the hood, I don't think the actual problem is under there. Likely in the dash, or under it, or even the gauge itself..... Might wanna run the circuit, and see if you find anything interesting in/under the dash.... That is, if it bothers you enough to wanna pretzel yourself under there.

 

I think I agree with you HY. This problem doesn’t seemingly exist among the prime suspects. It’s coming from a lower tier.

And yes, perhaps a dirty contact or a tempermental gauge. Although, my lights do flicker slightly so that tells me it’s a real problem in the charging system and not just a rogue gauge with a mind if its own. So I’m thinking your original thought… a bad or inadequate connection. BTW, the needle steadies up above idle. Even does better idling in PARK.

I admit I’m coming close to trying to live with it even though it triggers my OCD.

 

Just out of idle curiosity, did you have this problem before the regulator in the PCM went belly up?

 

I never had the regulator in the PCM go out on me. The microprocessor went out on my original PCM. I replaced it with a refurb and the regulator never worked on the refurb. It arrived that way.

I have thought about getting another refurb PCM with a working regulator. Probably from RockAuto this time instead of some rinky dink outfit like I did. At least RockAuto has some standards they expect to be met. My research of these external voltage regulators suggest those who had the same problem found that replacing it with a genuine Mopar regulator solved their problem. I cannot determine what the part number of the regulator is or what they used. I sorta doubt it is the regulator when it works then it doesn't work then I replace it with a new one and it doesn't work.

 

Hhhmmm..... Yeah, that's gonna be a fun one. And there is still the possibility that a new PCM won't solve it...... On you man. I wouldn't be at all surprised if the aftermarket voltage regulator didn't play a role here though. You could likely use ANY stock mopar voltage regulator from an older V-8 car though..... So far as I know, there really weren't any differences in them. After all, alternators all worked the same way, and dodge wanted the same output voltage on all of them.

 

Hmmmm. I’m trying to find what mopar regulator these people used. I’ll keep digging. I do have a lifetime guarantee on that PCM so I have the option of replacing it again. He was willing to when I discovered the regulator was not working in it. But I chose your option when you suggested I consider adding an external regulator. That was actually the second refurb he sent me. The first didn’t even start the truck. So I was happy the second one worked perfectly fine less the regulator that didn’t work. I liked your idea to add the bypass and do not regret that decision. I got 1-1/2 years of it working perfectly fine. I don’t know what happened starting last Fall that made it start dancing around.

Another thought. Your electronics knowledge is far better than mine so I’d be interested in your thoughts. I’m thinking I have a 90 amp alternator. Thinking that was stock and the reman I bought to replace it a few years ago was likely 90 amp. I think 120 amp alternators are readily available for my truck. Do you think it’s possible a 120 could make a difference?

 

It's possible, but, I wouldn't hold my breath. It's the output of the alternator that gets flaky..... WHY it gets flaky is the big question. Higher output won't hurt you, but, I don't think it'll solve the issue either. (but, I have been wrong before..... Yes, shocking, I know. )

 

I had an electrician tell me they don’t know why electricity does what it does most of the time either.

 

HY, I went back to my previous external regulator. The brand new regulator would measure 14.35 - 14.48v when I'd first start up the truck after sitting all night. It would vacillate rather rapidly in that range (along with the dash needle). After driving it 5+ miles I'd measure again and it would be 14.30 - 14.38v. Is it normal for the alternator output to drop a little after the engine is warmed up?

Anyway, I reinstalled my previous external regulator this morning. I know I have this regulator adjusted about 0.2v lower than the brand new one. Started up the truck and the needle was dancing around (+/- a volt or two). First couple of stop signs leaving the neighborhood it would dance. Went 3/4 mile down the road to the next stop sign and the needle was steady. Traveled another 5 - 7 miles with a half dozen or more stops. Needle steady the whole time at each stop I measured the output before I shut down the engine. 14.15v.

Just wondering if the dancing gets worse the higher the output at idle. I'll keep an eye (as usual) to see if I can see any pattern. Just wondering if you can make any sense of this. Could alternator output at idle make an impact on the dancing needle? Again, there is zero needle movement above 1000 RPM when you'd think there was HIGHER output.