Circuit/System Testing

2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
    WARNING: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.
    The High Voltage Disabling procedure will perform the following tasks:
    • Identify how to disable high voltage.
    • Identify how to test for the presence of high voltage.
    • Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.

    Failure to follow the procedures exactly as written may result in serious injury or death.
  1. Disable the high voltage for servicing at the drive motor generator control module assembly cable connections. Refer to High Voltage Disabling .
  2. Inspect for damaged 3 phase cables between the drive motor generator power inverter control module (PIM) and the transmission.
    • If damage is observed, replace the 3 phase cables.
  3. Remove the 3 phase cable assembly from the PIM distribution box. Refer to Generator Control Module 3-Phase Cable Assembly ReplacementΒ .
  4. Test the resistance of each phase by measuring between the following circuits with a DMM. You should measure 0.5 ohms or less.
    • Phase U and phase V
    • Phase U and phase W
    • If less than the specified value replace the PIM.
    • If more than the specified value continue with diagnosis.
  5. Disconnect the 3 phase cable assembly from the transmission. Refer to Generator Control Module 3-Phase Cable Assembly ReplacementΒ .
  6. Test each cable for continuity from the PIM connection terminal to the transmission connection terminal. You should measure 0.5 ohms or less.
    • If more than the specified value replace the 3 phase cable assembly.
    • If less than the specified value replace the drive motor generator assembly.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.