Circuit/System Testing

2006 Isuzu Ascender S, 5.3 M, 4WDSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 Isuzu Ascender, 2008 GMC Envoy, and 2008 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the automatic transmission shift lock actuator.
  2. Ignition OFF, test for less than 1.0 ohm between the ground circuit terminal A 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 control circuit terminal B and ground.
    • If the test lamp does not illuminate, test the park lock solenoid and A/T shift lock control solenoid control circuits for an open or short to ground. If all circuits test normal, test or replace the automatic transmission shift lock actuator.
  4. Ignition ON, verify that a test lamp illuminates between the control circuit terminal E and ground.
    • If the test lamp does not illuminate, test the A/T shift lock control solenoid control circuit for an open. If all circuits test normal, test or replace the stop lamp switch.
  5. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal E and ground when the brake pedal is depressed.
    • If the test lamp illuminates, test the A/T shift lock control solenoid control circuit for a short to voltage. If all circuits test normal, test or replace the stop lamp switch.
  6. If all circuits test normal, test or replace the automatic transmission shift lock actuator.
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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.