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.
Circuit/System Testing
2008 Pontiac Grand Prix BaseSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harness connector at the inside rearview mirror.
- Doors closed, courtesy lamps OFF, test for less than 5 ohms between the ground circuit terminal 8 and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Ignition ON, command the green LED OFF with a scan tool. Test for less than 1 volt between the control circuit terminal 14 and ground.
- If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the CIM.
- Command the green LED ON with a scan tool. Test for greater than 9 volts between the control circuit terminal 14 and ground.
- If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the CIM.
- Command the red LED OFF with a scan tool. Test for less than 1 volt between the control circuit terminal 15 and ground.
- If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the CIM.
- Command the red LED ON with a scan tool. Test for greater than 9 volts between the control circuit terminal 15 and ground.
- If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the CIM.
- If all circuits test normal, test or replace the inside rearview mirror.
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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.