Hello all,

I have a 1980 Toyota truck that was just acquired. It does not charge. The previous owner just put a new alternator and a new regulator into it. They don't even have dust on them. But there is no charging AT ALL.

The alternator has the big output stud sticking out the back and then a three wire connector.

I briefly connected 12V to each of the three connections on the back of the alternator. One of them causes the alternator to put out BIG TIME. So I believe the alternator is okay.

This leaves the wiring between the alternator and the regulator. The three wires from the regulator go up to a plug. They have continuity from the alternator end to regulator end plug. At the regulator plug one wire doesn't go thru because the regulator side doesn't have a matching wire.

At this point I opened the regulator but there is no figuring out what is happening under all that potting compound.

So I got a new regulator and plugged it in. No joy! Still not charging.

If I jumper from the HOT wire at the regulator connector to the little green wire(regulator unplugged) then the alternator again puts out maximum.

At this same connector one wire is always hot.

One is switched hot.

While the regulator is hooked up and the engine is running one wire is also at 11V.

One is at 10V.

The charge idiot light has never been seen and if I connect every wire in the harness to ground thru a 12V bulb the idiot light still doesn't come on. Should it?

Can the idiot light being burned out cause the alternator to cease output?

What are the three connections on the alternator? I can relate to a Delco alternator with the HOT stud and a field connector and the R connector for the idiot light but I can't figure out why the Toyota needs 3 wires plus the hot stud.

I purchased the Chiltons but all it has is a schematic showing:
Hot
Switched hot
Idiot light
and three "other wires between the regulator and the alternator but not what they do!!

With the regulator hooked up and engine running I never measure any voltage on that one wire that forces full alternator output.

Any suggestions?