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 G3500, Van Passenger ExtendedFACTORY OEM SERVICE PROCEDURE
Circuit/System Verification
- Ignition ON, verify that no starter relay, theft deterrent, or automatic transmission DTCs are set that would cause the ECM to disable starting.
- If DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- Ignition ON, observe the scan tool BCM Current Power Mode parameter. Place ignition switch in the crank position, the parameter should display Crank Request.
- If not the specified value, refer to Power Mode Mismatch .
- Transmission range selector in park, verify the scan tool ECM PNP Switch and TCM Park/Neutral parameters display Park/Neutral.
- If the TCM parameter does not indicate Park/Neutral. Refer to Range Selector Displays Incorrect Range for the 4L60/4L65/4L70- E transmission. or Range Selector Displays Incorrect Range (4.8L and 6.0L) or Range Selector Displays Incorrect Range (6.6L) for the 4L80/4L85- E transmission.
- If the ECM Park/Neutral parameter does not indicate Park/Neutral. Refer to ECM Park Switch Circuit Malfunction.
- Transmission range selector in park or neutral, attempt to start the vehicle. The starter relay should click and the engine should begin cranking.
- If the crank relay does not click or the engine does not crank, refer to Starter Relay Circuit Malfunction.
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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