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.
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6FACTORY OEM SERVICE PROCEDURE
Circuit/System Testing
- With the ignition ON, disconnect the ECM relay and observe with the scan tool for loss of communication.
- If the scan tool can still communicate with the vehicle, test the IGN 1 voltage circuit supplied by the ECM relay for a short to voltage. If the circuits test normal, replace the ECM.
- With the ignition OFF, probe the relay control circuit at the underhood electrical center with a test lamp connected to battery voltage.
- If the test lamp illuminates test the relay control circuit for a short to ground. If the circuits test normal, replace the ECM.
- With the ignition ON, probe the relay control circuit at the underhood electrical center with a test lamp connected to a good ground.
- If the test lamp illuminates, repair the short to voltage.
- If the test lamp does not illuminate, replace the relay.
IMPORTANT:
You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
Factory Service Tools
Use the Manual With the Right Hardware
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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.
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