1980 Toyota 4X4 20R, recently boiled a battery, had alternator tested, passed, put a new voltage regulator in, also have another new one on the way to see if that helps. Alternator overcharging battery, dummy light is on, wasn't on before due to a bad bulb, hence the boiled battery. got that all hashed out. so, new battery, alternator passed tests, new voltage regulator.

Still overcharging, battery reads 12.xx V at the posts with an accurate multimeter, increase throttle (RPMs) the voltage rises, up to 18 V..

i have the alternator pulled out, its an FEN type btw, wiring harness looks ok, although I do question why I have two wires coming off of my B post, both white with a blue stripe.

I'm stumped boys, any help? fresh thoughts? lay it on thick I need this rig working proper by monday.

 

new regulator in, wish me luck..

 

I can only guess your getting poor quality parts

You don`t mention just what parts your buying .

I wish I had schematics for that year I would only be guessing trying to trouble shooting

 

new reg didnt't do anything. its an Intermotor. probably a cheap one but you would expect it to work for at least a few minutes, right? might have to break down and find a toyota regulator

 

Seems like it would have to be the regulator. I don't see what else could cause the voltages to be that high. I've had a couple bad out of the box before. Very odd you would get two, however. Have you traced a wiring schematic and made sure all the wires are in place between the alt and voltage regulator? Been a while since I tore it into one but it seems like there is a wire that "tells" the regulator what the voltage is. if that was damaged/missing could cause overvoltage

 

Ill look into that rowdy, I believe the "sense" wire is the top wire in the alt side plug.

 

Think sense wire is a good call. Can even splice in another wire to check, essentially hotwiring sense to see if that changes voltage. Wire shorts can be a pain to track down.

 

sense wire goes to the...regulator? ill have to look at a diagram..again.

 

Just did a little research...one of the grounds that comes out of the loom where the alt plugs into the factory harness, is connected to the body, needs to be connected to the block. I have no idea if this will make a difference but I'm going to give it a try.

 

Pretty sure I nailed it, ran a set of wires of off the battery into the cab and hooked my multi-meter up, went for a drive and never made it over 14.8 V. although... MY DAMN CHARGE LIGHT IS STILL ON!! Wish I would've never discovered that the bulb had popped.

 

There is a relay mounted up under the dash on your far passenger side (may remove the glove box for easy access). As I recall it is grey in color. Mine went out and caused my charge light to stay on intermittently . Smack the P/S dash or slam the P/S door and see if it clears the light up. My guess is your relay is shot. When I checked, the toyota dealer can get the relay to a tune of about 80 bucks. You can make a standard SPST relay work but you will have to chop the toyota connector off. Or you could just take the relay out, but bear in mind the charge light will not function.

 

I just found one on the driver's side kick panel, black in color, unplug it and the light goes off.

 

What's it charging at now?

 

won't go above roughly 14.6 while driving it, if I sit in neutral and rev her high and hold, I'll get to nearly 15. Far cry from the 17-18 V I was getting revving by hand!