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 G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 2159 (ENGINE CONTROL SYSTEM & FUEL SYSTEM - 4.8L, 5.3L, 6.0L, 6.2L - DTC P1255 TO DTC P3449)DTC P1682CIRCUIT/SYSTEM VERIFICATION
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6
Circuit/System Verification
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Circuit/System Verification
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- If DTCs P0685, P0689, or P0690 are set, diagnose those DTCs first.
- Ignition ON, engine OFF, observe both the Ignition 1 Signal and the EC Ignition Relay Feedback Signal parameters on the scan tool. There should be no more than 3 V difference between the 2 parameters.
- 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.
NOTE:
On the scan tool, the powertrain relay is referred to as the EC ignition relay.
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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.