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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1988 (Engine Controls And Fuel - 2.4L - DTC P0010 To DTC P0315) >> DTC P0120, P0122, P0123, P0220, P0222, P0223, or P2135 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the throttle body. Allow sufficient time for the ECM to completely power down.
  2. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal C and ground.
    • If greater than 5 ohms, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal E and ground.
    • If less than 4.8 volts, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
    • If greater than 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  4. Verify the scan tool TP sensor 1 voltage is less than 0.1 volt.
    • If greater than 0.1 volt, test the signal circuit terminal D for a short to voltage. If the circuit tests normal, replace the ECM.
  5. Verify the scan tool TP sensor 2 voltage is greater than 4.8 volts.
    • If less than 4.8 volts, test the signal circuit terminal F for a short to ground. If the circuit tests normal, replace the ECM.
  6. Install a 3A fused jumper wire between the signal circuit terminal D and the 5-volt reference circuit terminal E of the TP sensor 1, verify the TP sensor 1 voltage is greater than 4.8 volts.
    • If less than 4.8 volts, test the TP sensor 1 signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
  7. Install a 3A fused jumper wire between the signal circuit terminal F and the low reference circuit terminal C of the TP sensor 2, verify that the TP sensor 2 voltage is less than 0.1 volt.
    • If greater than 0.1 volt, test the TP sensor 2 signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
  8. Ignition OFF, disconnect the harness connector at the ECM.
  9. Test for less than 5 ohms on all TP sensor circuits between the following terminals:
    • The 5-volt reference circuit terminal E to the corresponding ECM terminal
    • The signal circuit terminal F to the corresponding ECM terminal
    • The signal circuit terminal D to the corresponding ECM terminal
    • If greater than 5 ohms, repair the affected circuit.
  10. Test for infinite resistance between TP sensor 1 signal circuit terminal D and TP sensor 2 signal circuit terminal F.
    • If less than infinite resistance, repair the short between TP sensor 1 signal circuit and TP sensor 2 signal circuit.
  11. If all circuits test normal, replace the throttle body.
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