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#1
2002 GT 3.8 Alternator not charging
SE Level Member
12-23-2019
Hi all,
On my 2002 GP GT, 3.8, the alternator won't put out charging voltage to the battery. Took the alternator out and Advanced Auto says it is charging fine on their tester. Did a lot of internet searches and have a Haynes manual to trace wiring.
Fusible link leads at Starter solenoid seem to be good. The only thing I've been told that may be causing it is that the voltage regulator wires (harness) to the back of the alternator should show 12V on both pins when the engine is running. Haynes manual says there is a third (gray) wire, but I only have 2 (Orange and Red)
Summary. Engine off:
Alternator B+ lead = 12V
Regulator Orange wire = 12V
Regulator Red wire = 0V
Summary. Engine on;
Alternator B+ lead = 12V
Regulator Orange wire = 12V
Regulator Red wire = 5V approx.
I believe the above is correct, but I can't go back and test now since I have the battery and starter disconnected.
Traced the regulator wires per the Haynes manual and Orange tests through to the underhood general 10A fuse. Red tests through to the PCM. PCM looks OK. Clean, not burnt.
Hoping not to have to continue to trace wires..... Cleaned up a ground wire below the underhood fuse box, which seemed sketchy.
Any ideas on why there is not 12V to the back of the alternator on the Red wire, which I believe will enable the alternator to actually send out charging voltage?
Thanks all!
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