Thread: Electrical Help
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Old 03-29-2020, 11:40 AM   #2
Dead Parrot
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Join Date: Aug 2012
Location: Oklahoma City, OK
Posts: 2,472
Re: Electrical Help

Of the pair, the red wire should be hot as it runs to the junction box - it is a voltage sense wire that tells the alt how much voltage to make.

The other wire, brown IIRC, will have some voltage if the key is on. It serves as an excite source to get the alt started when the engine starts. If you have an Alt idiot light, the brown wire goes to that via the circuit board. If you have a voltmeter, IIRC, it goes to a resistance wire that is about the same resistance as the Alt idiot light.

As a guess, sounds like the old alt had a diode failure. That would have let current flow with the ignition off.
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