Alternator wiring, Had to do something today Options

[smrz914]

So I finally did something on my 914 v8. I couldn't stand not doing at least something on my car. There have been to many progress threads and then meeting club people at Parts Heaven today I had to get my fix (even if I didn't get enough of the fix). I want to do more work. I hooked up the idiot light. The alternator is a AC Delco 7127 that is internally regulated, 3-wire alternator.

wires:
1. Ground
2. Positive battery
3. Idiot light (#1 terminal on alternator)
4. #2 trerminal wire on alternator just goes to the positive post on the alternator. (not counted as a wire)

(IMG:http://www.rowand.net/Shop/Tech/images/AlternatorWiringOverview-1973to1985Buick.jpg)

For my 72 the idiot light wire is green/red. If you still have the relay board then the green/red wire goes to the number 5 spot (according to Haynes) and leaves the relay board as a green/red wire. I don't have a relay board so I just extened the green/red wire to the alternator. Maybe this can help someone with their v8.

[914GT]

Perfect timing Paul. I just got my engine back in the car today and tomorrow will finish up the installation. I had labeled the two wires for my alternator light and volt. sense, but didn't remember which terminal they went to.

[smrz914]

Awesome. It pays off to post stuff you have done, even if it's a little thing. Glad I could help somone on the board. So now I need to figure out some other projects that I can do without a garage.

[smrz914]

Is there a way to test to see if the idiot light is working? A test to see if the light will light when there is a problem with the alternator? I figure it's a good thing to check. Should I just disconnect the connector on the alternator? Thanks

[914GT]

QUOTE (smrz914 @ Jun 5 2005, 08:49 PM)

4. #2 trerminal wire on alternator just goes to the positive post on the alternator. (not counted as a wire).

This is the usual way to wire it but I connect a wire from terminal 2 to a junction terminal next to my battery. This regulates the voltage a little higher by cancelling out the voltage drops in the wiring.

[lapuwali]

I've never used a GM regulator, but that wiring diagram looks bizarre to me. The Bosch, Lucas, and Japanese internally regulated alternators all have a much simpler setup, where there's only the one fat wire to the + terminal on the battery, and one thin lead to the lamp, with the other terminal on the lamp going to switched +12. 100% of the field current then flows through the lamp until the alternator is self-energizing, when the lamp goes out as the voltage will now be equal on both sides.

Why the second thin lead from the regulator to unswitched +12? Why the bypass wire around the lamp?

[914GT]

Looking at the source of Paul's image it's off a Buick restoration website, so it's not exactly the same as the 914's wiring at the alternator light. The #2 terminal is a high-impedance sense input for the regulator. You can connect it right at the output and it will regulate at that point. If you connect it to a point closer to the load it will regulate the voltage from that remote point in the system, and the alternator will put out a higher voltage. I wired mine this way so I could get a little higher voltage at my electric water pump.

[914GT]

QUOTE (smrz914 @ Jun 5 2005, 09:54 PM)

Is there a way to test to see if the idiot light is working?

Just disconnect the wire from the alternator and touch it to ground, the light should come on with the ignition on.

This post has been edited by 914GT: Jun 10 2005, 09:31 AM

[Dave_Darling]

QUOTE (smrz914 @ Jun 5 2005, 07:49 PM)

For my 72 the idiot light wire is green/red. If you still have the relay board then the green/red wire goes to the number 5 spot (according to Haynes) and leaves the relay board as a green/red wire.

Wrong idiot light wire. That's for the oil pressure warning light.

On a 914, the light to the alternator warning light is blue.

--DD