924Board.org

[d12-Matt]

I found out today that the red wires are supposed to go to ground and the black ones go to the positive connections on the starter motor. In the process I seem to have damaged the alternator. Are all the wires on 924's backwards like that? Also, what's a good price for a remanufactured alternator?

[Diesel]

I've got a good one, e-mail me if you want it.

[924_fan]

According to the wiring diagram:
The red leads go from starter terminal 30 to B+ on the alternator. Terminal 30 is directly connected to the + terminal on the battery. The alternator case and the starter case are grounded.

[d12-Matt]

You mean that one terminal has both a red wire and a black wire leading to it?

[924_fan]

This description may get confusing as it is far easier to look at a wiring diagram for the info.

Starter terminal 30 is the large terminal that connects to the battery (the large positive battery cable). The alternator is using this as a "direct" connection to the battery.

Starter terminal 16 has a black wire going to the ignition (with a resistor in line). This supplies power to the ignition when the starter is engaged.

Starter terminal 50 has a red/black wire that eventually connects to the start position on the ignition switch.

The alternator has 3 connections:
B+ to the battery via the starter.
D+ eventually gets to the alternator light in the instrument panel.
And the ground wire connecting to the engine block.

Alternator D+, Starter 50, and Alternator 16 all use a three conductor Amp connector that sits on the right side by the firewall.

Usually, Porsche ground wires are brown.

[d12-Matt]

Hey thanks. I just tried setting up all the wires like that and the alternator mysteriously came back to life. Lesson learned: I shouldn't just connect wires where I think they ought to go, because chances are I'm wrong.

[wdb]

I got a bid from a auto electric shop ,for $80 they would rebuid mine.