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sprinkles08
sprinkles08, ASE Certified Technician
Category: Pontiac
Satisfied Customers: 22368
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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No power to alternator signal wire. cooling fans not coming

Customer Question

no power to alternator signal wire. cooling fans not coming on. tested signal wire from alternator to pcm and it is good
JA: Is the power loss consistent, or does it fluctuate?
Customer: consistent
JA: What is the model/year of your Pontiac?
Customer: 1994 bonneville se
JA: Are you fixing your Bonneville yourself? What have you tried so far?
Customer: yes a mouse chewed several wires all have been repaired . changed PCM still no power to alternator and fans
JA: Anything else you want the mechanic to know before I connect you?
Customer: all repaired wire were solder and shrink wraped
Submitted: 7 months ago.
Category: Pontiac
Expert:  kwiggins29059 replied 7 months ago.

Hello, is this the supercharged engine? What color is the wire you arre refering to as the "signal wire"

Customer: replied 7 months ago.
Not supercharged red signal wire
Expert:  kwiggins29059 replied 7 months ago.

Thanks, ***** ***** few moments while I look over the diagrams.

Expert:  kwiggins29059 replied 7 months ago.

I'm going to have to open this up to other experts for you, my diagrams are not showing the wire pin out at the ECM. SOmeone should be with you shortly.

Expert:  sprinkles08 replied 7 months ago.

Hello and welcome to JustAnswer!

The wire from the alternator to PCM does not control the alternator. The alternator is internally regulated and not controlled by the PCM. The red wire is a signal from the alternator regulator to the PCM that closes when voltage is out of normal range and then the PCM sends a signal to the instrument cluster to illuminate the battery light.