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.
  1. Ignition OFF, disconnect the harness connector at the MAF/IAT sensor.
  2. Ignition OFF for 90 seconds, test for less than 5 ohms between the low reference circuit of the IAT Sensor terminal D and ground.
    • If greater than the specified range, test the low reference circuit for high resistance. If the circuit tests normal, replace the ECM.
  3. Disconnect the harness connector at the IAT sensor 2.
  4. Ignition OFF for 90 seconds, test for less than 5 ohms between the low reference circuit of the IAT sensor 2 terminal B and ground.
    • If greater than the specified range, test the low reference circuit for high resistance. If the circuit tests normal, replace the ECM.
  5. Disconnect the harness connector at the ECM.
  6. Test for less than 5 ohms between the IAT Sensor signal circuit terminal E and the corresponding terminal at the ECM.
    • If greater than the specified range, repair the high resistance on the signal circuit.
  7. Test for less than 5 ohms between the IAT sensor 2 signal circuit terminal A and the corresponding terminal at the ECM.
    • If greater than the specified range, repair the high resistance on the signal circuit.
  8. If all circuits test normal, test or replace the affected temperature 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:

  • 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.