2002 GMC Sierra PCM

2002 GMC SIERRA
60,000 MILES • V8 • 2WD • AUTOMATIC
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SIERRA3223
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I just had my truck detailed and they power washed my engine. Since then my battery light keeps coming on. Took it for service and they asked me if I had the engine cleaned recently. Said water probably got into the PCM and it might need to be replace and I should take it to a dealer. very expensive. codes P1637 & P1638 were set. Really? The brain of my truck needs to be replace due to moisture?? They did all the standard tests and everything checked out ok, truck runs fine. I just read on another question that the PCM's dont go out very often? I should check for/ask dealer to check for specific shorted sensors? Please educate me.
Aug 2, 2008 at 7:15 PM
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MERLIN2021
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Nope! Thes are both alternator codes, 1637 is the L terminal, for the warning lamp, and 1638 is for the field terminal circuit, they may have ruined the alternator, but the PCM is probably OK..
Aug 2, 2008 at 7:27 PM