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P1638 Diagnostic Trouble Code Discussion for February 2010

TCM Internal - CAN 1 RAM Performance

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Trouble Ticket Help Requests for DTC P1638
Help Request Posted
2001 Chevrolet Express 3500 5.7L Poor Idle Quality, Misfire, MIL Lamp on VIN: 1GBHG31R61
P1638: Generator 'F' Terminal Circuit Malfunction. ... lacks power, and check engine light is on. Scan for trouble codes. P0335, P1637, P1638. I scoped the CKP signal wire at the PCM. Had a square wave signal. Checked power and ground at CKP sensor. Checked out ok. Perform voltage drop test between PCM and CKP...
February 10, 2010