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DTC P0120 (THV) - THROTTLE POSITION (TP) SENSOR CIRCUIT MALFUNCTIONCIRCUIT MALFUNCTION Subaru Outback BG

Testing & Diagnostics ~502 words
  1. Turn ignition off. Connect SSM. Start Engine. Set SSM function mode to F07 to check TP sensor output signal. If displayed voltage is less than 0.1 volt, go to next step. If displayed voltage is 0.1 volt or greater, go to step 7).
  2. Turn ignition off. Ensure throttle valve is fully closed. Turn ignition on. Using DVOM connected to chassis ground, backprobe ECM harness connector terminal No. 21. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-26255) article. If voltage is 4.5 volts or greater, go to next step. If voltage changes to greater than 4.5 volts while wiggling harness and connector, repair poor contact in harness or ECM connector. If voltage remains less than 4.5 volts, replace ECM.
  3. Backprobe ECM harness connector terminal No. 6. If voltage is 0.1 volt or less, go to next step. If voltage is greater than 0.1 volt while wiggling harness and connector of ECM, repair poor contact in harness or ECM connector. If voltage remains less than 0.1 volt, go to next step.
  4. Turn ignition off. Disconnect TP sensor harness connector. Turn ignition on. Check voltage between TP sensor connector terminal No. 3 and chassis ground. If voltage is 4.5 volts or greater, go to next step. If voltage is less than 4.5 volts, check for open circuit in harness between TP sensor and ECM connector. Check for poor contact in ECM and TP sensor harness connector.
  5. Turn ignition off. Disconnect ECM harness connector. Check resistance between ECM harness connector terminal No. 6 and TP sensor harness connector terminal No. 2. If resistance is less than one ohm, go to next step. If resistance is one ohm or greater, check for open in harness between TP sensor and ECM connector, or check for poor terminal contact in ECM and TP sensor.
  6. Check resistance between TP sensor harness connector terminal No. 2 and chassis ground. If resistance is less than 10 ohms, check for short in harness between TP sensor and ECM connector. If resistance is 10 ohms or greater, check for poor terminal contact in TP sensor or connector.
  7. If value is greater than 4.9 volts, go to next step. If value is 4.9 volts or less, check for poor terminal contact in ECM and TP sensor connectors. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-26255) article. Check for poor terminal contact in harness coupling connector.
  8. Turn ignition off. Disconnect TP sensor harness connector. Check resistance between TP sensor harness connector terminal No. 1 and chassis ground. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or greater, check for open in harness between ECM and TP sensor connector, and for poor terminal contact.
  9. Turn ignition on. Check voltage between TP sensor harness connector terminal No. 2 and chassis ground. If voltage reading is greater than 4.9 volts, check for short to voltage in harness between ECM and TP sensor connector. If voltage reading is 4.9 volts, replace TP sensor.

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