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 G3500, VAN PASSENGER EXTENDEDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 329 (HYBRID ENGINE CONTROL SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P1AF8 OR P1AFECIRCUIT/SYSTEM TESTING
2008 Chevrolet Chevy Express G3500, Van Passenger Extended
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.
- 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.
- Disable the high voltage for servicing at the drive motor generator control module assembly cable connections. Refer to High Voltage Disabling .
- Inspect for damaged 3 phase cables between the PIM and the transmission.
- If damage is observed, replace the 3 phase cables.
- 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.
- Remove the 3 phase cable assembly from the PIM distribution box. Refer to Generator Control Module 3-Phase Cable Assembly Replacement .
- 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 applicable drive motor generator assembly and retest for the DTC. If the DTC resets, replace the PIM.
- If more than the specified value, continue with diagnosis.
- Remove the 3 phase cable assembly cover from the transmission and inspect the 3 phase cable terminal fasteners for the proper torque and for arc-flash damage. Refer to Generator Control Module 3-Phase Cable Assembly Replacement .
- 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 applicable drive motor generator assembly and the 3 phase cable assembly.
- Disconnect the 3 phase cable assembly from the transmission. Refer to Generator Control Module 3-Phase Cable Assembly Replacement .
- 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 applicable drive motor generator 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.