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Circuit/System Testing

  1. Verify none of the following conditions exist:
  2. Ignition OFF, disconnect the harness connector at the throttle body assembly.
  3. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal 1 and ground.
    • If greater than specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
    4. IMPORTANT: The 5-volt reference circuits are internally and externally connected at the ECM. Other component DTCs may be set. If other DTCs are set, review the electrical schematic and diagnose the applicable circuits and components.
  4. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 2 and ground.
    • If less than the specified range, test the 5-volt reference circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the ECM.
    • If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  5. Ignition ON, verify the scan tool TP sensor voltage parameter is less than 0.3 volt.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  6. Install a 3A fused jumper wire between the signal circuit terminal 3 and the 5-volt reference circuit terminal 2. Verify the scan tool TP sensor voltage parameter is greater than 4.8 volts.
    • 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 ECM.
  7. Ignition OFF, connect the harness connector of the throttle body assembly.
  8. Disconnect the harness connector at the MAP sensor.
  9. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal 3 and ground.
    • If greater than specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  10. Ignition ON, verify the scan tool MAP sensor parameter is less than 12 kPa.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
    11. IMPORTANT: The 5-volt reference circuits are internally and externally connected at the ECM. Other component DTCs may be set. If other DTCs are set, review the electrical schematic and diagnose the applicable circuits and components.
  11. Test for 4.8-5.2 volts between the 5-volt reference circuit terminal 1 and ground.
    • If less than the specified range, test the 5-volt reference circuit for a short to ground or open/high resistance. If the circuits tests normal, replace the ECM.
    • If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  12. Install a 3A fused jumper wire between the signal circuit terminal 2 and the 5-volt reference circuit terminal 1. Verify the scan tool MAP sensor pressure parameter is greater than 102 kPa.
    • 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 ECM.
  13. If all circuits test normal, test or replace the MAP sensor.
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