Internal regulator alternator conversion on ‘71T

[tonytuzz]

OK, I have the factory bulletin on retrofitting an alternator with internal regulator to an earlier car, but it doesn’t cover what to do with the regulator connections on a pre-74.

So, once I remove the regulator on my ‘71T, I’m left with three wires: brown, blue, and black.

I presume brown just grounds back to the chassis, and black is unused, but what do I do with the blue wire?

[PeteKz]

Wrap some tape around it and tuck it up under the relay panel. Don't cut it off. It is paired to a blue wire that goes to the alternator and a blue wire that goes to the alternator light in your instruments.

[tonytuzz]

Originally Posted by PeteKz

Wrap some tape around it and tuck it up under the relay panel. Don't cut it off. It is paired to a blue wire that goes to the alternator and a blue wire that goes to the alternator light in your instruments.

Of course. I never cut wires, even when the factory bulletin tells me to;-)

I’m having trouble understanding how the old regulator did anything if it can be completely removed from the circuit and the circuit still functions.

I know I’m missing something simple.

[PeteKz]

The black wire went from the old VR to the field windings in the old alternator. It doesn't do anything now, because the new alternator has the VR mounted in the case itself. The other end of the old back wire should not be connected to the new alternator either.

[tonytuzz]

Originally Posted by PeteKz

The black wire went from the old VR to the field windings in the old alternator. It doesn't do anything now, because the new alternator has the VR mounted in the case itself. The other end of the old back wire should not be connected to the new alternator either.

I get that part, but aren’t the blue and brown still needed? I know blue runs to the dash light, can’t remember what brown does.

I have the factory manual, but the diagrams are pretty small, and I’m away on a biz trip. With a little head scratching and my reading glasses, I could probably figure it out, but I figured someone might have an easy answer.

So you’re saying the brown and blue don’t matter? Just wrap them up and tuck them out of the way?

[tonytuzz]

Here’s what I’ve got. I removed the red and the capacitor.

[PeteKz]

Brown is ground. You can screw that down under a chassis screw, or just leave it hanging. At the other end it's attached to the alternator, but it's redundant because the much larger brown wire goes from the alternator frame to the engine case to provide ground.

Blue wire is needed, and one leg of that circuit should be connected to one of the terminals on the alternator. As I said, it provides signal to the alternator light and to the old VR. It also provides excitation current to the alternator via the alternator light. If the alternator works and you don't have the alternator light on, then you connected it correctly.

[tonytuzz]

Thanks for your patience. Hopefully this thread will help some more folks.

I’ve connected the new Valeo alternator like this, found in another thread. The terminals on the new alternator were not labeled.

With the key on, the dash light is on, but the starter does nothing. Battery is fully charged, and starter was reliable prior to alternator replacement.

Any thoughts?

[PeteKz]

Re not "cranking": The yellow wire from the ignition switch goes through the engine wiring harness to the solenoid on the starter. Check for 12V at the spade terminal on the starter solenoid while an assistant turns the key to START. If no voltage, you probably knocked something loose while you were replacing the alternator. You just have to find it.

There are lots of threads here about starters not cranking, so refer to those too.