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Home › Chevrolet › 2007 › Optra LS, Standard › Repair and Diagnosis › Engine Performance › System › Engine Controls And Fuel - 1.8L (LDA) › Diagnostic Information and Procedures › DTC P0122 or P0123 › Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector of the TP sensor.
  2. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit of the TP sensor and ground.
    • If greater than 5 ohms, test the low reference circuit of the TP sensor for a short to voltage, or an open/high resistance. If the circuit/connections test normal, replace the ECM.
    3. 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.
  3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit of the TP sensor and ground.
    • If less than 4.8 volts, test the 5-volt reference circuit of the TP sensor for a short to ground or open/high resistance. If the circuit/connections test normal, replace the ECM.
    • If greater than 5.2 volts, test the 5-volt reference circuit of the TP sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.
  4. Using a scan tool, verify the TP sensor voltage parameter is less than 0.3 volt.
    • If greater than 0.3 volt, test the signal circuit of the TP sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.
  5. Install a 3-amp fused jumper wire between the signal circuit and the 5-volt reference circuit of the TP sensor. Verify the TP sensor voltage parameter is greater than 4.8 volts.
    • If less than 4.8 volts, test the signal circuit of the TP sensor for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the ECM.
  6. If all circuits/connections test normal, test or replace the TP sensor.
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