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    Case Study: Silverado’s antitheft light on, does not crank, no PCM communication

    Oct. 27, 2022
    This vehicle was towed in as a no-crank, no-start condition.
    Related To: ALLDATA
    2004 Silverado Alldata 63124829aeb6c

    Vehicle: 2004 Chevy Silverado 1500, 4WD, V6-4.3L, VIN X, Automatic Transmission/Transaxle

    Mileage: 192,664

    Problem: This vehicle was towed in as a no-crank, no-start condition.

    Case Details: The battery and starter were tested and checked out good. The technician attempted to retrieve codes, but the powertrain control module (PCM) would not communicate with the shop’s scan tool.

    Alldata Silverado Schematic
    Courtesy of ALLDATA
    Using a wiring diagram from ALLDATA Repair, the technician inspected all connections and found that ground, G103 was loose.
    Using a wiring diagram from ALLDATA Repair, the technician inspected all connections and found that ground, G103 was loose.

    An ALLDATA Tech-Assist consultant recommended verifying the condition of all 12V power connections, grounds and network communication lines to the PCM. Using a wiring diagram from ALLDATA Repair, the technician inspected all connections and found that ground, G103 was loose.

    Confirmed Repair: The tech cleaned the contact surfaces and then tightened the ground connection. After the repairs, normal communication, cranking, and starting resumed. Fixed!

    Reprinted with permission from ALLDATA.

    About the Author

    Richard Diegle | Senior Automotive Editor for ALLDATA

    Rich Diegle has been in the automotive industry since 1978. After graduating from a local community college, he began working at a Nissan dealership as a used car technician. Since then, he’s worked as a Nissan and ASE master automotive technician, shop owner, marketing copywriter, automotive editor, public relations manager, instructor, ALLDATA Tech-Assist team manager, and a senior automotive editor. 

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