Circuit/System Verification

2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Circuit/System Verification
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. Perform this verification procedure only when the ignition has been OFF for 8 hours or more.
  2. Ignition ON, observe the scan tool IAT and ECT sensor parameters. The ECT, IAT, and ambient temperature should be within 15Β°C (27Β°F) of each other.
  3. Engine running, observe the scan tool IAT Sensor parameter. The reading should be between -39 to +120Β°C (-38 to +248Β°F) depending on the current ambient temperature and the vehicle operating conditions.
  4. Ignition ON, observe the scan tool start-up ECT and start-up IAT Sensor parameters. Compare those sensor parameters to each other and also to the ambient temperature to determine if the IAT sensor is within an acceptable operating range.
  5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
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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.