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 2369 (ENGINE CONTROLS AND FUEL - 3.6L - DTC P0201 TO DTC P0629)DTC P0351-P0356 (LF1)CIRCUIT/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 2010 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harness connector at the appropriate T8 ignition coil.
- Ignition OFF, and all vehicle systems OFF, it may take up to 2 minutes for all the systems to power down. Test for less than 5 Ξ© between the ground circuit terminal A and ground.
- If greater than the specified range, repair the ground circuit for an open/high resistance.
- Ignition OFF, test for less than 5 Ξ© between the low reference circuit terminal B and ground.
- If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
- Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal D and ground.
- If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition voltage circuit fuse is open, test all components connected to the ignition voltage circuit and replace as necessary.
- Engine running, observe the Ignition Coil 1-6 Control Circuit Low Voltage Test Status on the scan tool. Test Status should be Ok or Not Run.
- If test status is Malfunction test for open or short to ground.
- Engine running, observe the Ignition Coil 1-6 Control Circuit Open Test Status on the scan tool. Test Status should be Ok or Not Run.
- If test status is Malfunction test for open circuit.
- Engine running, observe the Ignition Coil 1 6 Control Circuit High Voltage Test Status on the scan tool. Test Status should be Ok or Not Run.
- If test status is Malfunction test for short to voltage.
- If all circuits test normal, test or replace the T8 ignition coil.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.