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 MANUALSCHEVROLET2008CHEVY EXPRESS G3500, VAN PASSENGER EXTENDEDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 249 (ENGINE CONTROLS AND FUEL - 4.4L - DTC P0650 TO DTC P2544)DTC P1682CIRCUIT/SYSTEM VERIFICATION
2008 Chevrolet Chevy Express G3500, Van Passenger Extended
Circuit/System Verification
2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Circuit/System Verification
WARNING: This page is about a different car, the 2008 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
- If DTCs P0685, P0690, or B1380 are set, diagnose those DTCs first.
- Ignition ON, engine OFF, observe the Ignition 1 signal, and the EC Ignition Relay Feedback Signal parameters, on the scan tool. Both parameter values should display no more than 3 volts difference, between the 2 parameters.
- Ignition OFF, observe the ignition 1 voltage signal parameter, on the scan tool. The parameter value should be 0 volts, before the ECM powers down.
- Engine running, observe the DTC information with a scan tool. DTC P1682 should not set.
- Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
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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.