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Home >> Cadillac >> 2006 >> STS Base, 3.6 7, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 10 (Engine Control System - 4.4L - DTC P0010 To P0175) >> DTC P0120, P0122, P0123, P0220, P0222, P0223, or P2135 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Ignition OFF, disconnect the harness connector at the throttle body. Allow sufficient time for the ECM to completely power down. This can be verified by a no communication message on the scan tool.
  2. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal 3 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 5-volt reference circuit terminals 5 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 less than 5.2 volts, test the affected 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 1 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 2 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 1 and the 5-volt reference circuit terminal 5 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 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 2 and the low reference circuit terminal 3 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 of resistance on all TP sensor circuits between the following terminals:
    • ECM C2 signal circuit terminal 64 to TP terminal 1
    • ECM C2 signal circuit terminal 66 to TP terminal 2
    • ECM C2 5-volt reference circuit terminal 29 to TP terminal 3
    • If greater than 5 ohms, repair the affected circuit for open/high resistance.
  10. Test for infinite resistance between TP sensor 1 signal circuit terminal 1 and TP sensor 2 signal circuit terminal 2.
    • If less than infinite resistance, repair the short between TP sensor 1 signal circuit and TP sensor 2 signal circuits.
  11. If all circuits test normal, replace the throttle body.
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