Need help with alternator plug wires...
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Joined: Oct 2006
Posts: 82
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From: Stockton California
Need help with alternator plug wires...
My 85 came with a one wire alternator and I replaced it with a standard AC Delco unit. I have the thick (10 gauge?) wire taken care of, but the plug was missing from my harness. I took the complete plug from a parts car 86 but the 86 is slightly different from the 85. What does the plug on the alternator do for the 85? Will the car work fine without it? Thanks in advance
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Joined: Jun 1999
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From: Merritt Ils Fl
NO, it will not work without something goin into the plug. The plug shoulg have two wires, a red (not the 10 ga) and a brown/white. The red goes to the starter solenoid (one of the three fusible links). The B/W runs thru a resistor to the ignition switch and a power distribution system. These two wires provide the field voltage which is required for the alternator to function. I wager that if you look in the wire bundel running from the alternator area you will find these two wires cut and taped.
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Joined: Oct 2006
Posts: 82
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From: Stockton California
I peeked into the harness but didn't find anything out of the ordinary. However, I have a thick (10 gauge) red wire sitting in the engine bay coming from the transmission area. It has voltage coming through the wire so I have it taped off at the moment. I drove the car the other day around the block and it ran alright. I will tear apart that harness and see what I come up with
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Joined: Oct 2006
Posts: 82
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From: Stockton California
I figured out that my mystery 12 gauge red wire was coming from my starter and that it runs to the alternator plug. I now have the thin brown wire to take care of. I cannot figure out where the wire taps into. If I could find the sensor/location that the brown/white alternator plug wire goes to, I could run it directly to that location. I really need to figure this one out so I can drive the car, thanks in advance-
Le Mans Master
Joined: Sep 2006
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From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
wires
8 gauge red thick wire on alternator goes to a battery lead through a fusible link to positive.
red wire in little plug goes to battery for volts reference.
white black goes to a bulb on the diagnostic panel that glows amber when the alternator isn't putting out.
your digital dash should over-ride the coolant temp readout when it isn't within parameters.
If it is working, you should see the coolant temp return.
try temporarily going to an auto parts store and getting an alternator plug. Then hook up a light bulb to the black wire and battery to the little red wire. see if it charges by putting a volt meter on the battery and checking for 13.5+ volts.
red wire in little plug goes to battery for volts reference.
white black goes to a bulb on the diagnostic panel that glows amber when the alternator isn't putting out.
your digital dash should over-ride the coolant temp readout when it isn't within parameters.
If it is working, you should see the coolant temp return.
try temporarily going to an auto parts store and getting an alternator plug. Then hook up a light bulb to the black wire and battery to the little red wire. see if it charges by putting a volt meter on the battery and checking for 13.5+ volts.
