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 781 (HYBRID/EV CONTROL SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P0AF7CIRCUIT/SYSTEM VERIFICATION
2008 Chevrolet Chevy Express G3500, Van Passenger Extended
Circuit/System Verification
2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Circuit/System Verification
WARNING: This page is about a different car, the 2011 GMC Yukon, 2011 Chevrolet Tahoe, and 2011 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition ON, observe the scan tool accessory DC power control module heat plate temperature and engine coolant temperature (ECT) parameters in freeze frame data. The accessory DC power control module heat plate temperature reading should be less than 105°C (221°F).
- If the accessory DC power control module heat plate temperature parameter reading was greater than 105°C (221°F) and the engine coolant temperature (ECT) was greater than 125°C (257°F) in freeze frame data, refer to Symptoms - Engine Cooling and correct that concern first.
- Inspect for proper coolant level in the hybrid cooling system reservoir.
- If coolant level is low refer to Hybrid Cooling System Loss of Coolant .
- Inspect hybrid cooling hoses for pinches or obstructions.
- If a concern is found, repair or replace hoses as necessary.
- Inspect the hybrid cooling system radiator for debris or obstruction. Refer to Engine Overheating
.
- If a concern is found, repair or replace the restricted or damaged components as necessary.
- Inspect for proper operation of all hybrid system coolant pumps. Refer to Hybrid Cooling System Overheating (Electrical)
.
- If a concern is found, repair or replace the coolant pumps as necessary.
- Command the cooling fans through all operating speeds.
- If the cooling fans do not operate in all speeds, refer to Cooling Fan Inoperative (without HP2) , Cooling Fan Inoperative (with HP2) .
- Separate the T6 drive motor generator power inverter module from the K1 accessory DC power control module. Inspect the T6 drive motor generator power inverter module and K1 accessory DC power control module cooling surfaces for excessive corrosion or contamination restriction. Refer to Drive Motor Generator Power Inverter Module Removal and Installation .
- If a corrosion or contamination is found, clean the K1 accessory DC power control module and drive motor generator power inverter module cooling surfaces. If corrosion is severe enough to prevent cleaning of the cooling surfaces replace the K1 accessory DC power control module.
- Replace K1 accessory DC power control module if no concerns are found.
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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.