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Alternator Problems

Old 08-03-2011, 10:46 PM
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Join Date: Aug 2011
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Exclamation Alternator Problems

Well, here it is. One day my "Check Charging System" and battery light came on. When I checked, I had no voltage output going to the battery. I ordered a alternator from Napa and installed it. Right when I started it the "Check Charging System" came on and the battery light stayed on.

I have brought it to a shop and they pulled a P0620 code. I have checked the B+ wire from the alternator to the battery and have very little voltage drop, if any. I have checked the grn/org wire from the Alternator to the PCM and no Voltage Drop. I checked the org/blu wire from the Alternator to the battery, and have no voltage drop.

I back probed the org/blue wire while the engine is running and show 14.1 volts. I back probed the grn/org wire while the engine was running and showed 13.8.
The all data wiring diagram shows and 8-9v at the PCM. I have unplugged the connector at the alternator and checked the grn/org wire with the engine running and still show 12v.

Here is my question, I think the PCM may be bad, but I called to price one and it the dealer quoted me $1600.00. This is not something I want to guess at. Does anyone have some more ideas for me to check before I start looking at replacing the PCM? Should I have only 8-9v on the grn/org wire?

Thank you everyone in advance.

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