× Auto Repair Pros Member Benefits TechHelp Knowledge Base Forums Resources My iATN Marketplace Chat Pricing About Us Join Industry Sponsors Video Members Only Repair Shops Auto Pro Careers Auto Pro Reviews
Join Now
International Automotive Technicians Network

P1638 Diagnostic Trouble Code Discussion for February 2010

TCM Internal - CAN 1 RAM Performance


Note: This is a professional automotive technician's resource.
Vehicle Owners: If you are seeking an automotive repair professional to service your vehicle, visit the iATN Repair Shop Finder.

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