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 DIAGNOSISENGINE MECHANICALCOOLING SYSTEM (MECHANICAL)ENGINE COOLING SYSTEMDIAGNOSTIC INFORMATION AND PROCEDURESDTC P0526CIRCUIT/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
- Ignition OFF, disconnect the fan clutch at the shroud.
- Measure between the low reference circuit terminal C and ground for less than 3 ohms.
- If more than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
- Ignition ON, measure between the 5-volt reference circuit terminal E and the low reference circuit terminal E for 4.8-5.2 volts.
- If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
- If more than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Install jumper wires in the 5-volt reference and low reference circuits between the harness and pigtail connectors at the shroud.
- 5-volt reference circuit terminal E
- Low reference circuit terminal C
- Measure DC voltage between the signal circuit terminal at the sensor pigtail connector and the 5-volt reference circuit jumper wire terminal.
- Ignition ON, rotate the fan by hand. The voltage should toggle between approximately 5 volts and 0 volts.
- If the voltage does not toggle correctly, test the three circuits in the pigtail harness for a short to ground, a short to voltage, or an open/high resistance. If the circuits test normal, replace the clutch.
- Leave the jumpers from the previous step in place. Measure voltage between the signal circuit terminal D at the harness and pigtail connectors at the shroud.
- Rotate the fan by hand. The voltage should toggle between approximately 5 volts and 0 volts.
- If the voltage does not toggle correctly, test the signal circuit for a short to ground or a short to voltage. If the circuit tests normal, replace the ECM.
- If all circuits and the speed sensor test normal, replace the ECM.
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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.