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FD alt in S4 chassis, won't excite at startup

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Old May 27, 2012 | 03:21 PM
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FD alt in S4 chassis, won't excite at startup

I have looked at the drawings again and again, here is how I am running it.

B - 12V through the stock connection. I put the S4 alt b post on the FD alt.
S - (White/Blue on FD plug) is run direct to battery. I know it should be fused but I want it to work first.
L - (White/Black on FD plug) is run to a Brown/Yellow wire.


My alternator plug had a Black/White wire and a Brown/Yellow wire. Everyone talks about the white/black black/white plug but I swear I don't have that plug.

I am running a haltech, most of the stock wiring to the engine has been replaced. The alt excites when I rev the engine (well, it did when before I rebuilt the engine) and I want to put this issue to rest.

Am I crazy and somehow wired into the wrong plug from the stock wiring? I have no other plug now and this is the same plug that ran my S4 alt....
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Old May 27, 2012 | 03:34 PM
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disconnect and see if you get 12v at either of the small gauge wires with the key on, if not then there is your issue.
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Old May 28, 2012 | 01:13 AM
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Looking at the engine diagram I have been a complete moron, I have the air bypass solenoid wire.

I found a cut white/black wire with red stripes as the third, this wire is 0v off and 12v at ACC/ON. Is this the wire I am looking for?

Based on the wiring diagram it looks correct, the white/black wire is the same source as the black/white wire just switched off a relay.
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Old May 28, 2012 | 09:04 AM
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Originally Posted by farberio
Looking at the engine diagram I have been a complete moron, I have the air bypass solenoid wire.

I found a cut white/black wire with red stripes as the third, this wire is 0v off and 12v at ACC/ON. Is this the wire I am looking for?

Based on the wiring diagram it looks correct, the white/black wire is the same source as the black/white wire just switched off a relay.
Ground the W/B wire and w/key to on it should force the idiot lights to light up. If it does then that's your wire.
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Old May 28, 2012 | 12:38 PM
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I don't have idiot lights anymore, but I wired it in and it came alive when I started the car. Joy!

For the S, can I wire that into the black/white wire from the old plug? It looks like its on a +12 line or does it have to be +12V 100% of the time?
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Old May 28, 2012 | 12:43 PM
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if you don't need an ammeter then don't worry about the other wire.
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Old May 28, 2012 | 01:05 PM
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The old connectors black/white wire is not connected and my ammeter works fine. Then again I have no idea if its the correct black/white wire.
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Old May 28, 2012 | 01:11 PM
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From: tulsa,ok.
Originally Posted by farberio
I don't have idiot lights anymore, but I wired it in and it came alive when I started the car. Joy!

For the S, can I wire that into the black/white wire from the old plug? It looks like its on a +12 line or does it have to be +12V 100% of the time?
S terminal requires a constant voltage source.
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Old May 28, 2012 | 01:17 PM
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Thanks, I will take the time to wire it up correctly and it should put this whole issue to bed.

Both satch and karack, thank you much.
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