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 512 (ENGINE COOLING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P0526CIRCUIT/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 does not describe the selected car, but rather 6 other vehicles, including the 2009 GMC Savana Special, 2009 GMC Savana Camper Special, 2009 GMC Savana, 2009 Chevrolet RV Cutaway, and 2009 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
- 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.