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 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.
  1. Ignition OFF, disconnect the harness connector at the TC vane control solenoid.
  2. Ignition ON, verify that a test lamp illuminates between the TC high control circuit terminal A and ground.
    • If the test lamp does not illuminate, test the high control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
  3. NOTE: When the engine coolant temperature is less than 70Β°C (158Β°F), the test lamp will change brightness when commanded with a scan tool. When the ECM is attempting a TC Learn, the test lamp will flash ON and OFF without commands from a scan tool.
  4. Connect the J 34730-405Β  between the high control circuit terminal A and the low control circuit terminal B.
  5. Engine running, engine coolant temperature (ECT) sensor 1 must be less than 70Β°C (158Β°F). Command the TC Vane Pos. Ctrl. Solenoid ON and OFF with a scan tool. The test lamp should illuminate and change from bright to dim when changing between the commanded states.
    • If the test lamp does not illuminate, test the low control circuit terminal B for an open/high resistance or a short to voltage. If the circuits test normal, replace the ECM.
    • If the test lamp remains illuminated, test the low control circuit terminal B for a short to ground. If the circuit tests normal, replace the ECM.
  6. Ignition OFF, test for a resistance between 2-7 Ξ© across the terminals of the TC vane control solenoid.
    • If the resistance is not within the specified range, replace the TC vane position solenoid.
  7. Test for infinite resistance between each terminal and the TC vane control solenoid housing.
    • If less than infinite resistance, replace the TC vane control solenoid.
  8. If all circuits test normal, replace the TC vane control solenoid.
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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.