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 1175 (CRUISE CONTROL SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P0571CIRCUIT/SYSTEM TESTING
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6
Circuit/System Testing
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harness connector of the stop lamp switch.
- Ignition ON, verify that a test lamp illuminates between the stop lamp switch voltage circuit terminal B and ground.
- If the test lamp does not illuminate, test the stop lamp switch voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the RUN/CRANK Relay.
- Ignition OFF, disconnect the harness connectors of the BCM X5, ECM X1, TCM (if equipped), Power Take Off (PTO) module (if equipped) and Trailer Brake controller (if equipped).
- Ignition OFF, verify that a test lamp does not illuminate between the stop lamp switch harness terminal A and B+.
- If the test lamp illuminates, test the brake switch signal circuit for a short to ground.
- Test for less than 1.0 ohm resistance between the stop lamp switch harness terminal A and one of the following:
- ECM connector X1 terminal 83 for the 6.6L engine.
- ECM connector X1 terminal 55 for the 4.3L engine.
- ECM connector X1 terminal 9 for the 4.8L, 5.3L, 6.0L, 6.2L or 7.0L engines.
- If resistance is not as specified, test the stop lamp switch circuit for an open/high resistance.
- Ignition ON, verify that a test lamp does not illuminate between the stop lamp switch TCC brake signal circuit terminal A and ground.
- If the test lamp illuminates, test the brake switch signal circuit for a short to voltage.
- If all circuits test normal, test or replace the stop lamp switch. If the component and all circuit tests are normal, replace the 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.