Well, 5 Voltage Regulators Later....And

[Lockedhearts]

Big Blue is still having issues with charging (both over and under). We have replaced both batterys, the alternator, and are now on our 5th VR, this time we got the $50 some dollar one and replaced the plug for the VR and added 2 extra ground wires.
Picked it up yesterday from the mechanic and it was charging fine on the way home. This morning it started intermittently overcharging(I know it was not a gauge glitch as it was dark and my lights were on and they got brighter)
and then going back to normal. Mechanic thinks the Alternator may have gone bad (less than a month old)
So any ideas?

 

[kcw12]

id replace the VR and the Alt at the same time.

 

[hoodshauler]

I think the alternator is the problem, that may also be why you have gone thru so many voltage regulators. The alternator may have to get hot before it shows it's bad side but I would change it.

 

[6 Nebraska IDIs]

I had all kinds of wiring problems with my red truck. Pulled and cut a while pile of wire out of it that didnt belong. Had all kinds of charging problems, because they cut and wired a car alternator in it. Ended up burning up 2 sets of batteries, 7 VR's, one radio, and a set of tail lights.
Ended up being my brand new alternator, the one I replaced the stupid car one with, had a short in it and would fry the VR in just a few seconds.

 

[Double-S-Diesel]

sawp the alt out for one from a 90ish tauras, 130 amp interanlly regulated, all ya need is the wire harness, and hook a few wires up.

 

[bluecollar]

Ditto on the alternator. I just went through the same problem a while back. Installed new vr with new alt. and after truck warmed up voltage needle would peg out and then fluctuate with rpms. Changed vr three times and finally changed alternator and all is fine now. That's been a couple of months ago now.

 

[swampdigger]

What year is your truck? Is it externally regulated? A bad connection between the regulator and alternator could cause exactly what you describe to happen! I'd redo all the connections.

The regulator has a wire leading to the battery to tell it how many volts is present, and it adjusts the alternator proportionately. If the connection is poor, it will get a misleading reading, and cause the alternator to output the wrong voltage.