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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G3500, VAN PASSENGER EXTENDEDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 10 (ENGINE CONTROL SYSTEM & FUEL SYSTEM - 6.6L (LMM) - DTC P0016 TO DTC P0299)DTC P0047 OR P0048CIRCUIT/SYSTEM TESTING
2008 Chevrolet Chevy Express G3500, Van Passenger Extended

Circuit/System Testing

2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Circuit/System Testing
WARNING: This page is about a different variant/trim than selected.
  1. Ignition OFF, disconnect the harness connector at the TC vane control solenoid.
    2. IMPORTANT: When the engine coolant temperature is less than 70°C (158°F), the test lamp will change brightness when commanded with a scan tool. When the engine coolant temperatures are above 70°C (158°F), the test lamp will flash ON and OFF without commands from a scan tool.
  2. Connect the J 34730-405  between the high control circuit terminal A and the low control circuit terminal B.
  3. Engine running, engine coolant temperature (ECT) sensor 1 must be less than 70°C (158°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 circuit tests normal, test the high control circuit terminal A for a short to ground or an open/high resistance. 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.
  4. Ignition OFF, test for a resistance between 2-7 ohms across the terminals of the TC vane control solenoid.
    • If the resistance is not within the specified range, replace the TC vane position solenoid.
  5. 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.
  6. If all circuits test normal, replace the TC control 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:

  • • 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.