High Voltage Spiking - Troubleshooting Help Needed

[RWWinslow]

The voltage will occasionally spike to 16 VDC for a couple of minutes and then returns to normal. Usually this happens shortly after starting the engine, but it can happen while driving down the road. The grid heaters still work and cycle normally after a cold start. All other electrical components are normal. When the voltage is high the headlights get pretty bright (gives the Moose a bit of a headache) but there do not seem to be any other consequences of this problem at this time. Any ideas as to source of the problem? (voltage regulator, alternator, and battery new in 2004)

 

[TWorline]

I would have to think it is the voltage regulator not working correctly. It would definitly be the easiest to change!

 

[mysteryman]

An intermittent short in the field wiring or inside the alt. itself will cause this. If you have a 91. 0 it should have a voltage regulator on the firewall... Many of the after market voltage regulator's do not work very well with the alt's on our trucks! Try buying one from your Dodge dealer... And NEVER unplug or plug it in under power. It will blow the voltage regulator instantly.

 

[JLEONARD]

And those firewall mounted regulators do have a reputation of going bad so replacing it will be a good thing.

 

[mysteryman]

a partially shorted cell in the battery can also cause the voltage to spike as you described... .

 

[pepecat]

Staying clear of marine Deep Cycle Batteries would be a good choice as well. I have gone thru a few of those Deep cycle batteries you buy @ costco over the past couple of years until finally installing a proper group 31 battery inside. I was having voltage spikes as the cells would always begin to short out in "short notice"

 

[RWWinslow]

Thanks for the insight - I will try the voltage regulator path first. I have seen VR's fail and provide low output. Will advise on success. . . . .

 

[GIT-R-DONE]

Check your connector plug on the VR too. Mine was corroded to the pont of intermitent contact from rust. A small dremel tool took care of that along with electrical grease.

 

[hdm48]

Over the years I have found two things to be a constant. Voltage regulators will drive a truck owner nuts, and a bad ground (voltage regulator) will do the same thing.

But just to prove I can never stop learning, the simple little plug at the regulator can and will go bad and cause what you are experiencing.

 

[drury]

I just had this exact problem in my 3rd gen and it turned out to be a loose ground cable on one of my batteries.

 

[GIT-R-DONE]

What did you end up finding out about your problem, just a follow up.