Circuit/System Testing

2006 Isuzu Ascender S, 4.2 S, 4WDSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2007 Isuzu Ascender, 2007 GMC Envoy, 2007 Chevrolet TrailBlazer, and 2007 Buick Rainier. However, it is still accessible from the selected car via links, so may be relevant.
    IMPORTANT: All electrical components and accessories must be turned OFF and allowed to power down.
  1. Ignition OFF, disconnect the MAF/IAT harness connector at the MAF/IAT sensor.
  2. Ignition OFF, test for less than 5 ohms of resistance between the ground circuit terminal B and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal C and ground.
    • If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
  4. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal A and ground.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PCM.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the PCM.
  5. If the MAF sensor circuits test normal, test the frequency output of the MAF sensor. Refer to Component TestingΒ  for instructions.
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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.