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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1672 (HYBRID CONTROLS - DTC P181C TO DTC P2797)DTC P1AF8 OR P1AFECIRCUIT/SYSTEM TESTINGNOTES
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6

Circuit/System Testing: Notes

2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Notes
WARNING: This page is about a different car, the 2009 GMC Sierra and 2009 Chevrolet Silverado. 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 PIM and the transmission.
    • If damage is observed, replace the 3 phase cables.
  3. Inspect the 3 phase cable terminal fasteners for the proper torque and for arc-flash damage.
    • If any fasteners were loose and no arc flash damage is present, torque the fasteners and re-assemble the vehicle. Retest for the DTC.
    • If any fasteners were loose and arc flash damage is present, replace the PIM and the 3 phase cable assembly.
  4. Remove the 3 phase cable assembly from the PIM distribution box. Refer to Generator Control Module 3-Phase Cable Assembly Replacement .
  5. Test the resistance of each phase by measuring between the following circuits with a DMM.
    • Phase U and phase V
    • Phase U and phase W
    • If you measure 0.5 ohms or less, continue with Circuit/System Testing.
    • If you measure more than 0.5 ohms, proceed to Open Phase Testing Procedure below.
  6. Test the resistance to ground for each phase of the applicable drive motor generator by measuring between the following points with a DMM.
    • Phase U terminal and chassis ground
    • Phase V terminal and chassis ground
    • Phase W terminal and chassis ground
    • If infinite resistance is measured, replace the 3-phase cable assembly and the drive motor generator assembly that corresponds to the set DTC and retest for the DTC. If the DTC resets replace the PIM.
    • If less than infinite is measured, continue with Circuit/System Testing.
  7. Remove the 3-phase cable assembly from the transmission. Refer to Generator Control Module 3-Phase Cable Assembly Replacement . Ensure the terminals are not contacting chassis ground.
  8. Retest the resistance to ground for each phase of the 3-phase cable. Measure between the following points with a DMM.
    • Phase U terminal and shield ground
    • Phase V terminal and shield ground
    • Phase W terminal and shield ground
    • If infinite resistance is measured, replace the applicable drive motor generator.
    • If less than infinite is measured, replace the generator control module 3-phase cable assembly.
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

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