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 1185 (ENGINE CONTROLS AND FUEL - 6.6L - DTC P02E7 TO DTC P0699)DTC P064CCIRCUIT/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 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition ON, verify the scan tool GPCM Ignition 1 Signal parameter is battery voltage.
- If the Ignition 1 Signal parameter is not battery voltage, test the battery positive voltage circuit to the glow plug control module for an open or short to ground. If the circuit tests normal, replace the GPCM.
- Ignition OFF, disconnect the X2 harness connector at the GPCM.
- Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal 52 and ground.
- If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the GPCM.
- Ignition ON, verify that a test lamp illuminates between the ignition 0 voltage circuit terminal 53 and ground.
- If the test lamp does not illuminate, test the ignition 0 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the GPCM.
- If all circuits test normal, replace the GPCM.
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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.