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Test DH: Throttle Position Sensor: Testing

    NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  1. 1) DTC P0120: Check
    DTC P0120 indicates PCM received an excessively high or low voltage, a high voltage under light load driving conditions, or a low voltage under heavy driving conditions from TP sensor. Possible causes for this fault are:
    • TP sensor circuit is open, or shorted to GND or VPWR.
    • Faulty TP sensor.
    • Faulty Fuel injector.
    • Faulty CMP sensor.
    • Faulty MAF sensor.
    • Intake air leaks.

    Visually inspect throttle linkage and throttle plate for binding or sticking. Ensure that throttle plate and linkage is at closed throttle position. If throttle plate is binding or sticking, repair and repeat QUICK TEST . If throttle plate and linkage is okay, go to next step.

  2. 2) Check TP PID

    Turn ignition off. Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, access TP PID from PID/DATA MONITOR & RECORD menu. If TP PID is .35-4.60 volts, leave scan tool connected and go to step  30). If TP PID is less than .35 volt, go to step  10). If voltage is more than 4.60 volts, leave scan tool connected and go to step  20).
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 2) to step 10). No test procedures have been omitted.

  3. 10) Check VREF Circuit Voltage To TP Sensor

    Disconnect TP sensor connector. Turn ignition on. Using DVOM, measure voltage between VREF and SIG RTN circuits at TP sensor harness connector. See Figure. If voltage is about 4.5-5.5 volts, go to next step. If voltage is less than 4.5 volts, go to TEST C  , step  2). If voltage is more than 5.5 volts, repair short to voltage on affected circuit. See WIRING DIAGRAMS article.

  4. 11) Simulate High TP Signal To PCM

    Turn ignition off. Connect a jumper wire between TP signal and VREF circuits at TP sensor harness connector. Turn ignition on. Using scan tool, access TP PID from PID/DATA MONITOR & RECORD menu. If TP PID reading is 4.5 volts or less, go to next step. If TP PID reading is more than 4.5 volts, replace TP sensor.

  5. 12) Check Continuity Of TP Circuit

    Turn ignition off. Disconnect PCM harness connector. Inspect connector for damaged pins and repair if necessary. Using DVOM, measure resistance of TP signal and SIG RTN circuits between TP sensor harness connector and PCM harness connector. See Figure and Figure . If both resistances are less than 5 ohms, go to next step. If either resistance is 5 ohms or more, repair open in circuit. See WIRING DIAGRAMS article.

  6. 13) Check TP Circuit For Short To Ground

    Leave TP sensor disconnected. Ensure PCM is disconnected. Using DVOM, measure resistance between TP circuit and SIG RTN, and GND circuits at PCM harness connector. See PCM TERMINAL CIRCUIT IDENTIFICATION  table. See Figure and Figure . If all resistances are more than 10 k/ohms, replace PCM. If any resistance is 10 k/ohms or less, repair short to GND or chassis ground in affected circuit.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 20). No test procedures have been omitted.

  7. 20) Simulate Low TP Signal

    Turn ignition off. Disconnect TP sensor connector. Connect a jumper wire between TP signal and SIG RTN circuits at TP sensor harness connector. See Figure. Turn ignition on. Using scan tool, access TP PID from PID/DATA MONITOR & RECORD menu. If TP PID is .2 volt or more, go to next step. If TP PID is less than .2 volt, replace TP sensor.

  8. 21) Check Continuity Of TP & SIG RTN Circuits

    Ensure ignition is off. Disconnect PCM harness connector. Inspect connector for damaged pins and repair if necessary. Using DVOM, measure resistance of TP signal and SIG RTN circuits between TP sensor harness connector and PCM harness connector. See Figure and Figure . If both resistances are less than 5 ohms, go to next step. If either resistance is 5 ohms or more, repair open in affected circuit. See WIRING DIAGRAMS article.

  9. 22) Check TP Signal Circuit For Short To VREF

    Ensure PCM and TP sensor harness connectors are disconnected. Using DVOM, measure resistance between TP and VREF circuits at PCM harness connector. See PCM TERMINAL CIRCUIT IDENTIFICATION  table. See Figure and Figure . If resistance is more than 10 k/ohms, replace PCM. If resistance is 10 k/ohms or less, repair short between circuits.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 30). No test procedures have been omitted.

  10. 30) Check TP Sensor Output

    Turn ignition on. Using scan tool, access TP PID from PID/DATA MONITOR & RECORD menu. Slowly open throttle from idle to WOT position while observing TP PID reading. Compare TP PID voltage reading to specifications. See THROTTLE POSITION SENSOR OUTPUT  table. If TP PID output voltage does not agree with specification, replace TP sensor. If TP PID output voltage agrees with specification, fault may be intermittent. Go to TEST Z  , step  1), or go to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - VILLAGER article.
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