Hello all. I have read some past threads about this with lots of troubleshooting info but wanted to try to narrow it down some more.

Have the center console, factory volt meter. Noticed for the first time yesterday it was below 12v when I was driving. Was on a 400 mile mission and the volts kept going down so I knew it was not charging. I saw the needle "spike" to 13+ volts for a minute or two and then back to less than 12. I made it home and by then nothing electrical was functioning. The meter was on zero or less volts and charging "idiot light" was NOT lit. Also I have somewhat of an oil leak that has covered the alternator and probably saturated it. Understand that there is an internal regulator but don't want to start randomly replacing parts.

So since this seemed to be sudden and there was a spike and then failure and no light I will check the bulb first and then fuses. The battery is newer and terminals clean. This is just a wood hauler and occasional over the road heavy hauler so I'm not up for putting tons of cash into it and replacing everything trial and error but will never part with it either. Any other Quick checks? Thanks again...

 

I would check the voltage directly at the battery with a meter, both before you start it up (resting voltage, or see how dead it is) and after starting. Watch the voltage when you rev the motor and stuff. Would the truck re-start after you got it home?

 

I would first fix the oil leak before anything. Sounds like a dead alt. Or just keep charging the battery every time before ya go out,

 

Break out the Meter get some real numbers .

Alternators and oil don`t play well together .

Fix your oil leak then your electrical problems

 

Changed the charge bulb which was dead. Still did not light up. traced it to the relay which was the problem. The bulb is lit but stays that way now. No voltage coming from alternator as checked with meter. So will be changing that. Will be cleaning up the motor in search of the leak.

"just keep charging the battery every time before ya go out, "

(Not a bad idea,,,)

 

internal regulator on an 81? regulator on drivers fender well

 

I want to say yes, it's got external regulator on an 81. I don't think they swapped to internal until somewhere around like 83/84 but could be wrong, I just know it's early 80s from all the alternator researching I did before doing a GM alt swap on my 75 hilux.

You can still get stock replacement alternators for external regulators. I chose the GM swap because it's got more amps for similar pricing.

 

OP said internal regulator, and I was questioning that. I believe they went internal in 85. I have an 84 in the yard with external. Sounds like he needs a regulator. there were 2 different ones (alternators, and regulators)in those years as well. Michael

 

I just had the same problem with my truck and it turned out to be my external regulator located on the driver side under the hood right above the wheel well its a little square box with a bolt on each side and one wire connector to the harness. First I switched out my alternator for a brand new one which was free because it was warranted from February then I checked my regulator after that didn't work seeing how I had two lying around and what do you know I was getting a charge again. Alternator is only $45 O'Reilly's I'd recommend I'd recommend getting a new I'd recommend getting a new one first a picture with a course as stated above and if that doesn't fix your problem replace the regulator and you should be golden. My regulator went out simply because I disconnected my battery and removed it. Talking about unlucky little Gremlins