Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 2198 (HYBRID CONTROLS - DTC B008A TO DTC P0AF7)DTC P0A78 OR P0A79CIRCUIT/SYSTEM TESTING
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6
Circuit/System Testing
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Circuit/System Testing
WARNING: This page is about a different car, the 2010 GMC Sierra and 2010 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- 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.
- Perform the High Voltage Disabling procedure for servicing at the drive motor generator control module cable connections.
- Remove the 3-phase cable assembly from the PIM distribution box. Refer to Generator Control Module 3-Phase Cable Assembly Replacement .
- 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 PIM and retest for DTCs. If DTC P0A78 or P0A79 still resets, replace the 3-phase cable assembly and the drive motor generator assembly that corresponds to the set DTC.
- If less than infinite is measured, continue with Circuit/System Testing.
- 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.
- 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 chassis ground
- Phase V terminal and chassis ground
- Phase W terminal and chassis 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.
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:
Failure to follow the procedures exactly as written may result in serious injury or death.
The High Voltage Disabling procedure will perform the following tasks:
Failure to follow the procedures exactly as written may result in serious injury or death.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • 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.