Did you take the printed circuit board off the back of the cluster or just clean it with it still attached?

 

No, I just cleaned the two main circular connectors and disconnected a couple of small circuit boards attached to the main and wiped down those connections. I also inspected for blown capacitors, but didn't find any. Not really related, but I also got rid of the buzzer module down below on the fuse panel. It had a short or something that was screwing with the lighting circuit.

 

So I made a new ground cable. Used 10ga but instead of going from the regulator to the battery I went from the regulator to a ground stud on the alternator. Same ground I’ve had from Day 1 but 10ga instead of the 14ga that was there. First test drive and the dash gauge meter was pegged. Didn’t flinch one iota. Steady as can be. So I’ll keep an eye on it.

 

So I'm going to declare my truck voltage fluctuation problem fixed again. The 10ga ground cable I used to replace the 14ga wire that was on my regulator did the trick. That dash gauge needle doesn't move even in the slightest. You'd need a pry bar to get it off its perch (or a turn signal). I have the adjustable voltage regulator output set to 14.22v at idle with no accessories turned on. Hard to get an accurate setting on those. You think you got it and then you check it again and it settles in somewhere else. 14.22v is good enough!


So, in conclusion, if you add an external voltage regulator to your Dakota to bypass a failed internal regulator in your computer, I highly recommend the following:

1. Ensure ALL your connections are clean and solid. Once you are sure of this, check again. (Advice provided by Ralph).
2. Remove the fender/firewall paint from behind the regulator mount holes. Put a thin film of dielectric grease on the bare metal to prevent corrosion.
3. Use a 10ga ground cable going from the regulator mount screw to the alternator ground stud. 12ga may work too but I used 10ga cuz that's what I had.

 

And the dancing voltage gauge is back. Someone needs to explain to me how that needle could be rock steady for the better part of a week (after replacing the 14ga ground wire with a 10ga wire) then of its own volition start dancing around again. I certainly have no idea. I put in a new regulator too. Didn't help one iota.

Only thing left I can think of is to pull the instrument panel and start cleaning stuff. Never had it out before. Appears to be easy to pull it...that's not my concern. But what am I cleaning? Appears there are two main circular connectors on the back with 10/11 pins each. Assume I want to hit that with contact cleaner. Anything else while I have it out?

 

The alternator puts out a/c current, goes thru a rectifier to change it to DC. Wonder if yours is bad/marginal...

 

Wouldn't that show up on Advanced Auto Parts fancy scope?

 

You would think so.

I wonder if there just isn't some 'leakage', though why it would be so intermittent is beyond me. I suppose the only way to really tell for sure, would be to put it on an o-scope, and see what the output signal looked like.

 

I'm thinking that's what Advanced Auto Parts did, no? It was some kinda scope cuz he showed me the output graph on the screen. It was very tight and consistent with no stray spikes or valleys. He measured it for a good minute at idle and at 2500 RPM. The guy who read it said that alternator was very healthy (along with the battery and starter). It should. It doesn't have a lot of miles on it.

 

Interesting..... I think their scope is just reading DC voltage though. Not sure if it tests for leakage. (would have to ask 'em.) The fact you can make the problem go away for a while, makes me REAL curious what that is all about.