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 MANUALSCHEVROLET2008HHR LT, 2.4 P, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 662 (ENGINE COOLING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P0480 (2.2L OR 2.4L)CIRCUIT/SYSTEM TESTING
2008 Chevrolet HHR LT, 2.4 P, Automatic
Circuit/System Testing
2008 Chevrolet HHR LT, 2.4 P, AutomaticSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2011 Chevrolet HHR. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the cooling fan relay.
- Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.
- If the test lamp illuminates, test the control circuit for a short to voltage.
- Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the relay.
- Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
- Disconnect the harness connector at the cooling fan.
- Test for less than 1.0 ohm between the cooling fan ground circuit terminal A and ground
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Connect the harness connector at the cooling fan.
- Connect a 30A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the cooling fan is activated.
- If the cooling fan does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the cooling fan.
- Verify that a test lamp does not illuminate between the B+ circuit terminal 85 and the control circuit terminal 86.
- If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
- Ignition OFF, allow the ECM to completely power down.
- Test for 70-110 ohms between terminals 85 and 86 of the cooling fan relay.
- If the resistance is not within the specified range, replace the relay.
- Measure amperage with a DMM connected in series with the relay coil and a 3A fused jumper wire between the B+ circuit terminal 85 and the control circuit terminal 86.
- Ignition ON, command the relay ON and OFF with a scan tool. The DMM should indicate less than 1 mA with the relay commanded OFF and approximately 170 mA with the relay commanded ON.
- If the DMM does not indicate the specified values, test the control circuit for an open or a short to voltage. If the circuit tests normal, replace the ECM.
- If all circuits test normal, test or replace the cooling fan relay.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.