SFI SYSTEM, Diagnostic DTC:P2121

DTC Code DTC Name
P2121 Throttle / Pedal Position Sensor / Switch "D" Circuit Range / Performance

CAUTION / NOTICE / HINT

Tech Tips

This DTC relates to the accelerator pedal position sensor.

DESCRIPTION

Refer to DTC P2120 Click here.

DTC No. DTC Detection Condition Trouble Area
P2121 Difference between VPA and VPA2 is less than 0.4 V, or more than 1.2 V for 0.5 seconds (1 trip detection logic)

  • Accelerator pedal position sensor

  • ECM

FAIL-SAFE

The accelerator pedal position sensor has 2 (main and sub) sensor circuits. If a malfunction occurs in either of the sensor circuits, the ECM detects the abnormal signal voltage difference between the 2 sensor circuits and switches to limp mode. In limp mode, the functioning circuit is used to calculate the accelerator pedal opening angle to allow the vehicle to continue driving. If both circuits malfunction, the ECM regards the opening angle of the accelerator pedal as being fully closed. In this case, the throttle valve remains closed as if the engine is idling.

If a pass condition is detected and then the ignition switch is turned off, the fail-safe operation stops and the system returns to a normal condition.

WIRING DIAGRAM

Refer to DTC P2120 Click here.

INSPECTION PROCEDURE

Tech Tips

Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

PROCEDURE


  1. READ VALUE USING INTELLIGENT TESTER (ACCELERATOR POSITION NO. 1 AND ACCELERATOR POSITION NO. 2)


    1. A017G5YE14

      Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch on (IG) and turn the tester on.

    3. Select the following menu items: Powertrain / Engine and ECT / Data List / Accelerator Position No. 1 and Accelerator Position No. 2.

    4. Read the values displayed on the tester.

      Standard voltage
      Accelerator Pedal Operation ACCELERATOR POSITION NO. 1 (AP#1) ACCELERATOR POSITION NO. 2 (AP#2)
      Released 0.5 to 1.1 V 1.2 to 2.0 V
      Depressed 2.6 to 4.5 V 3.4 to 4.7 V

    NG

    CHECK HARNESS AND CONNECTOR (ACCELERATOR PEDAL POSITION SENSOR - ECM) Click here

    OK

  2. CHECK WHETHER DTC OUTPUT RECURS (ACCELERATOR PEDAL POSITION SENSOR DTCS)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch on (IG) and turn the tester on.

    3. Clear the DTCs Click here.

    4. Start the engine.

    5. Allow the engine to idle for 15 seconds.

    6. Select the following menu items on the tester: Powertrain / Engine and ECT / DTC.

    7. Read the DTCs.

      Result
      Display (DTC Output) Proceed to
      P2121 A
      No output B

    B

    SYSTEM OK

    A

    REPLACE ECM Click here

  3. CHECK HARNESS AND CONNECTOR (ACCELERATOR PEDAL POSITION SENSOR - ECM)


    1. A017C14E05

      Disconnect the accelerator pedal position sensor connector.

    2. Disconnect the ECM connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance (Check for open)
      Tester Connection Condition Specified Condition
      A19-6 (VPA) - D31-18 (VPA) Always Below 1 Ω
      A19-5 (EPA) - D31-20 (EPA) Always Below 1 Ω
      A19-4 (VCPA) - D31-26 (VCPA) Always Below 1 Ω
      A19-3 (VPA2) - D31-19 (VPA2) Always Below 1 Ω
      A19-2 (EPA2) - D31-21 (EPA2) Always Below 1 Ω
      A19-1 (VCP2) - D31-27 (VCP2) Always Below 1 Ω
      Standard resistance (Check for short)
      Tester Connection Condition Specified Condition
      A19-6 (VPA) or D31-18 (VPA) - Body ground Always 10 kΩ or higher
      A19-5 (EPA) or D31-20 (EPA) - Body ground Always 10 kΩ or higher
      A19-4 (VCPA) or D31-26 (VCPA) - Body ground Always 10 kΩ or higher
      A19-3 (VPA2) or D31-19 (VPA2) - Body ground Always 10 kΩ or higher
      A19-2 (EPA2) or D31-21 (EPA2) - Body ground Always 10 kΩ or higher
      A19-1 (VCP2) or D31-27 (VCP2) - Body ground Always 10 kΩ or higher

    4. Reconnect the accelerator pedal position sensor connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. REPLACE ACCELERATOR PEDAL


    1. Replace the accelerator pedal Click here.


    NEXT

  5. CHECK WHETHER DTC OUTPUT RECURS (ACCELERATOR PEDAL POSITION SENSOR DTCS)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch on (IG) and turn the tester on.

    3. Clear the DTCs Click here.

    4. Start the engine.

    5. Allow the engine to idle for 15 seconds.

    6. Select the following menu items on the tester: Powertrain / Engine and ECT / DTC.

    7. Read the DTCs.

      Result
      Display (DTC Output) Proceed to
      P2121 A
      No output B

    B

    SYSTEM OK

    A

    REPLACE ECM Click here