ECD SYSTEM, Diagnostic DTC:P1121

DTC Code DTC Name
P1121 Throttle / Pedal Position Sensor/Coolant Flow Control Valve Position Sensor Circuit Stuck

DESCRIPTION

Tech Tips


  • This is the repair procedure for the accelerator pedal position sensor.

  • The electrical throttle system does not use a throttle cable.

  • The accelerator pedal position sensor is a non-contact type.

The accelerator pedal position sensor is mounted in the accelerator pedal to detect the opening angle of the accelerator pedal. Since this sensor is electronically controlled with hall elements, accurate control and reliability can be obtained. It has 2 sensors to detect the accelerator position and a malfunction of the accelerator position sensor.

In the accelerator pedal position sensor, the voltage applied to pedal terminals VPA and VPA2 of the ECM changes between 0 V and 5 V, in proportion to the opening angle of the accelerator pedal. The VPA is a signal to indicate the actual accelerator pedal opening angle which is used for the engine control, and the VPA2 is a signal to indicate the information about the opening angle which is used for detecting a malfunction. The ECM judges the current opening angle of the accelerator pedal from these signals input from terminals VPA and VPA2, and the ECM controls the injection pump based on these signals.

A003DXVE06
DTC No. DTC Detection Condition Trouble Area
P1121 Either of the ECM sensors have completed learning and the electric potential difference of VPA and VPA2 sensors has become more than 1.2 V or less than 0.4 V.

  • Open or short in accelerator pedal position sensor circuit

  • Accelerator pedal position sensor

  • ECM

One of the following continues more than 2.0 seconds.


  1. When the electrical potential difference of VPA and VPA2 sensors is not within the specified range.

  2. VPA2 is 4.9 V or higher.

  3. Accelerator idling criterion voltage of VPA and VPA2 is less than 0.04 V.

WIRING DIAGRAM

A003ASHE40

INSPECTION PROCEDURE

Tech Tips

Read freeze frame data using the GTS. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, and other data from the time the malfunction occurred.

PROCEDURE


  1. READ VALUE USING GTS (ACCELERATOR POSITION)


    1. A003GTOE02

      Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON and turn the GTS on.

    3. Enter the following menus: Powertrain / Engine and ECT / Data List / Accel Sens. No.1 Volt % and Accel Sens. No.2 Volt %.

    4. Read the values.

      OK
      Check that the value displayed on the GTS changes by repeatedly depressing and releasing the accelerator pedal.

    NG

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

    OK

    REPLACE ECM Click here

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


    1. 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
      Tester Connection Condition Specified Condition
      B1-1 (VCP2) - B74-57 (VCP2) Always Below 1 Ω
      B1-2 (EPA2) - B74-56 (EPA2) Always Below 1 Ω
      B1-3 (VPA2) - B74-55 (VPA2) Always Below 1 Ω
      B1-4 (VCPA) - B74-58 (VCPA) Always Below 1 Ω
      B1-5 (EPA) - B74-59 (EPA) Always Below 1 Ω
      B1-6 (VPA) - B74-60 (VPA) Always Below 1 Ω
      B1-1 (VCP2) or B74-57 (VCP2) - Body ground Always 10 kΩ or higher
      B1-2 (EPA2) or B74-56 (EPA2) - Body ground Always 10 kΩ or higher
      B1-3 (VPA2) or B74-55 (VPA2) - Body ground Always 10 kΩ or higher
      B1-4 (VCPA) or B74-58 (VCPA) - Body ground Always 10 kΩ or higher
      B1-5 (EPA) or B74-59 (EPA) - Body ground Always 10 kΩ or higher
      B1-6 (VPA) or B74-60 (VPA) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ACCELERATOR PEDAL ROD ASSEMBLY Click here