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 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition ON, verify DTC P0615 is set as current.
- Ignition OFF, disconnect the crank relay, test for 60-80 ohms of resistance between relay terminals 85 and 86.
- If not within the specified range, replace the crank relay.
- Ignition ON, test for B+ between the crank relay coil supply voltage circuit terminal M4 and ground.
- If less than the specified value, test the supply voltage circuit for a short to ground or an open/high resistance.
- Ignition ON, connect a test lamp between the crank relay coil supply voltage terminal M4 and the crank relay control circuit terminal K5. Turn the ignition to the start position. The test lamp should only illuminate when the ignition is held in the start position.
- If the test lamp is always On, test the control circuit for short to ground.
- If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance.
- If the circuit tests normal replace the PCM/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.