ok so my 81 is having some sort of electical problem. i was on my way to work tuesday morning and i stopped at a gas station to get something to drink, i get ready to leave and my truck wouldnt start. but i did notice be for i stopped my wipers were moving really slow. anyway i call a buddy from work to give me a jump didnt work so i went and got a new battery and it started right up. then on my way home with my headlights on wipers goin and sterio cranked i saw that my volt meter was only reading 8 volts, so i stopped looked under the hood for anything that didnt look right and nothing so i turned the wipers, lights and sterio off and kept truckin tell i got home. so i changed out the alt. with a spare i had and its doin the same thing and now my new battery is dead. pretty much i dont know what to do, im not good with electrical so i really need some help
Well one nice thing about these older pickups is they are pretty simple. So you've got power to all of your bits and bobs so we know that its probably not fuse related. One question I have is your charge light on? Is the spare alternator working? But it seems to me like you should check the "converter box" (I know it has a name I just can't recall what it is) I know that in my 76 I had the a similar issue where it all seemed to get power but would peter out. When I took the box off the truck the back side was filled with dirt and spider webs so I figured it couldn't hurt and replaced it with the much fresher looking spare I had and that solved the issue. For me the box was on the drivers side mounted up under the lip of the fender in the engine bay, just behind the ignitor.
ya that would be the voltage regulator like curt said.. i do know that the vr on an 81 is built into the alt. but there was no charge light coming on and the alt. i put in must be working cause i disconnected the battery while it was running and it stayed running. the few people i had talked to said it could be a short somewheres in the system
people really need to stop doing that. you have a "alternator" not a "generator", thats a valid test with a generator, but it puts on way too much of a load on a alt, and can fry both alt and voltage regulator. sounds like the alt isnt working, what voltage do you have at the batt while running? whats the voltage @ the B+ terminal on the alt? i would blame the stock wiring if you've put in known good parts and still have a issue. the stock wiring gets super brittle off the back of the alt, and the main B+ wire craps out too.
not sure what the voltage is at the moment i cant find my tester im going to see if i can snag one from work so i should know tonight or tomorrow what they are reading
