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Home >> Dodge and Ram >> 2003 >> Durango Base, 5.9 Z, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 15 (Engine Controls - Self Diagnostics - 4.7L) >> Diagnostic Tests >> DTC P0121: Throttle Position Sensor #1 Performance >> Testing

DTC P0121: Throttle Position Sensor #1 Performance: Testing

WARNING: This page is about a different car, the 2003 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Diagnose any IAC motor or TP sensor DTCs first before continuing. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . The throttle plate and linkage should be free of binding and carbon build-up. Ensure the throttle plate is at the idle position. Inspect the engine for vacuum leaks and proper installation of the PCV valve, MAP sensor, IAC, and TP sensor.
  1. Ignition on, engine not running. With the DRBIII® scan tool, read DTCs and record the related freeze frame data. Is the Good Trip Counter displayed and equal to zero? If yes, go to next step. If no, see INTERMITTENT CONDITION  under SELF-DIAGNOSTIC SYSTEM.
  2. Ignition on, engine not running. With the DRBIII® scan tool, monitor the TP sensor voltage while slowly depressing the throttle pedal from the idle position to the wide open throttle position. Does voltage start at approximately 0.8 volt and go above 3.5 volts with a smooth transition? If yes, see INTERMITTENT CONDITION  under SELF-DIAGNOSTIC SYSTEM. If no, go to next step.
  3. Turn the ignition off. Disconnect the TP sensor harness connector. Disconnect the PCM harness connectors. Ignition on, engine not running. Measure the voltage on the (K22) TP sensor No. 1 signal circuit in the TP sensor harness connector. Is the voltage above 5.2 volts? If yes, repair the short to voltage in the (K22) TP sensor No. 1 signal circuit. If no, go to next step.
  4. Turn the ignition off. Connect the PCM harness connectors. Ignition on, engine not running. Connect a jumper wire between the (K22) TP sensor No. 1 signal circuit and the (K4) sensor ground circuit. With the DRBIII® scan tool, monitor the TP sensor voltage. Does the TP sensor voltage change from approximately 4.9 volts to below 0.5 volt? If yes, replace the TP sensor. If no, go to next step.
    NOTE: Remove the jumper wire before continuing.
    5. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis.
  5. Turn the ignition off. Disconnect the PCM harness connectors. Measure the resistance of the (K7) 5-volt supply circuit from the TP sensor harness connector to the appropriate terminal of Miller Special Tool (8815). Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair excessive resistance in the (K7) 5-volt supply circuit.
  6. Measure the resistance between ground and the (K7) 5-volt supply circuit at the TP sensor harness connector. Is the resistance above 1.0 ohm? If yes, go to next step. If no, repair the excessive resistance between the (K7) 5-volt supply circuit and ground.
    7. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis.
  7. Measure the resistance of the (K22) TP sensor No. 1 signal circuit from the TP sensor harness connector to the appropriate terminal of Miller Special Tool (8815). Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the excessive resistance in the (K22) TP sensor No. 1 signal circuit.
  8. Measure the resistance between ground and the (K22) TP sensor No. 1 signal circuit at the TP sensor harness connector. Is the resistance above 100 k/ohms? If yes, go to next step. If no, repair the short to ground in the (K22) TP sensor No. 1 signal circuit.
    9. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis.
  9. Measure the resistance of the (K4) sensor ground circuit from the TP sensor harness connector to the appropriate terminal of Miller Special Tool (8815). Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the excessive resistance in the (K4) sensor ground circuit.
    10. NOTE: Before continuing, disconnect the PCM harness connectors and check the related wiring terminals for corrosion, damage or terminal push out. Repair as necessary.
  10. There are no possible causes remaining, replace PCM. Program the new PCM. See PROGRAMMING .
  11. Ignition on, engine not running. With the DRBIII® scan tool monitor the TP sensor voltage. Slowly open the throttle from the idle position to the WOT position. Does voltage start at approximately 0.8 of a volt and go above 3.5 volts with a smooth transition? If yes, see INTERMITTENT CONDITION  under SELF-DIAGNOSTIC SYSTEM. If no, replace the TP sensor.
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