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 1801 (ENGINE CONTROLS AND FUEL - 4.4L - DTC P0010 TO DTC P0158)DTC P012C OR P012DCIRCUIT/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 2009 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
You must perform the Circuit/System Verification before proceeding with the Circuit/System Testing.
- Verify the integrity of the SCIAP sensor system by inspecting for the following conditions:
- Any damage to the SCIAP sensor housing
- A loose or improperly installed SCIAP sensor
- A restriction in the vacuum source of the SCIAP sensor
- Ignition OFF, disconnect the harness connector at the SCIAP sensor.
- Ignition OFF for 90 seconds, test for less than 5 ohms between the low reference circuit and ground.
- If greater than the specified range, test the low reference circuit terminal A for an open/high resistance. If the circuit tests normal, replace the ECM.
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal C and ground.
- If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
- Verify the scan tool SC Inlet Pressure Sensor parameter is less than 20 kPa.
- If the greater than the specified parameter, test the signal circuit terminal B for a short to voltage. If the circuit tests normal, replace the ECM.
- Install a 3A fused jumper wire between the 5-volt reference circuit terminal C and the signal circuit terminal B. Verify the scan tool parameter is greater than 95 kPa.
- If less than the specified parameter, test the signal circuit for a short to ground, open/high resistance. If the circuit tests normal, replace the ECM.
- If all circuits test normal, test or replace the SCIAP sensor.
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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.