Circuit/System Testing

2006 Isuzu Ascender S, 5.3 M, 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.
  1. Ignition OFF, disconnect the harness connector at the AIR solenoid valve.
  2. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the control module.
  3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal and ground.
    • If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the control module.
    • If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the control module.
  4. Verify the scan tool AIR Pressure Sensor parameter is less than 0.5 volt.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the control module.
  5. Install a 3A fused jumper wire between the signal circuit terminal and the 5-volt reference circuit terminal. Verify the scan tool AIR Pressure Sensor parameter is greater than 4.9 volts.
    • If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the control module.
  6. If all circuits test normal, test or replace the AIR solenoid valve.
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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.
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