Voltage regulator confusion with my 1976 FJ40 (2 Viewers)

[chrischavarro]

Hey everyone! My 1976 FJ40 has been dead reliable apart from the oil pressure, fuel, and temperature gauges not working. I’m guessing it may be due to the absolutely gnarly aftermarket voltage regulator that’s seen better days. I ordered an OEM replacement from @ToyotaMatt earlier this year and noticed that it consists of a single plug. However, the existing regulator has four wires leading out of it, two that end in the same style plug, one that I believe serves as a ground, and another that runs into the cabin and is wrapped around the engine fuse in the fuse box. I wanted to request some insight as to whether the ground and engine fuse wires are required when replacing the voltage regulator or if it’s just the nature of the aftermarket part. I figured I’d ask here before I just started pulling stuff out and creating a major headache for myself. I’d really appreciate the help!

 

[45Dougal]

There are two types.
I'm not sure if you can make it work though.

 

[chrischavarro]

I did see that later model year FJ40s have the green plug for the voltage regulator, which mine does not. It does plug in just fine, it’s just a matter of determining why there’s a wire that feeds into the fuse box from the regulator, as the OEM Denso unit doesn’t seem to have anywhere for that wire to go into.

 

[45Dougal]

Ah I see.
Well one of the three wires should be a green-red wire feed from the engine fuse, so weird that someone has bypassed it with a hack - switch on the ignition and see if it is live. Maybe it got burnt out in the past?
Some people also fitted a charge light on the dash which will stop you charging if the bulb is blown.

Another one of the three is black- white which should be connected to ground at the alternator (I think), so you shouldn't need a second ground wire. Check for continuity to ground.

The third wire is the white-green field wire to the alternator.

Check continuity and you should be good.