ECD SYSTEM (w/ DPF), Diagnostic DTC:P0122, P0123

DTC Code DTC Name
P0122 Throttle / Pedal Position Sensor / Switch "A" Circuit Low Input
P0123 Throttle / Pedal Position Sensor / Switch "A" Circuit High Input

DESCRIPTION

The throttle position sensor is mounted on the diesel throttle body assembly and detects the opening angle of the throttle valve. This sensor is an electronic sensor and uses Hall-effect elements.

When the throttle valve is fully closed, a voltage of approximately 0.7 V is applied to terminal VLU of the ECM. The voltage applied to terminal VLU of the ECM increases in proportion to the opening angle of the throttle valve and becomes approximately 3.5 to 4.0 V when the throttle valve is fully opened.

The ECM determines the vehicle driving conditions from the signals input to its VLU terminal. The data is one of the pieces of information used for EGR control, etc.

A003I7CE03
P0122
DTC Detection Drive Pattern DTC Detection Condition Trouble Area
Ignition switch ON for 3 seconds Throttle position sensor output (VLU) is below 0.2 V for 3 seconds (1 trip detection logic).

  • Throttle position sensor

  • Open or short in VLU circuit

  • Open in VC circuit

  • ECM
P0123
DTC Detection Drive Pattern DTC Detection Condition Trouble Area
Ignition switch ON for 3 seconds Throttle position sensor output (VLU) is higher than 4.8 V for 3 seconds (1 trip detection logic).

  • Throttle position sensor

  • Open in E2 circuit

  • VC and VLU circuits are short-circuited

  • ECM

Tech Tips

If DTC P0122 and/or P0123 is stored, the following symptoms may appear:


MONITOR DESCRIPTION

When the output voltage of the throttle position sensor deviates from the normal operating range (between 0.2 V and 4.8 V) for more than 3 seconds, the ECM interprets this as a malfunction of the sensor circuit and illuminates the MIL.

A003DOOE09

WIRING DIAGRAM

A003BX3E02

INSPECTION PROCEDURE

Note


  • After replacing the ECM, the new ECM needs registration Click here and initialization Click here.

  • After replacing the fuel supply pump assembly, the ECM needs initialization Click here.

  • After replacing an injector assembly, the ECM needs registration Click here.

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. CHECK HARNESS AND CONNECTOR (THROTTLE POSITION SENSOR - ECM)


    1. Disconnect the throttle 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
      t1-1 (VC) - D99-97 (VCVL) Always Below 1 Ω
      t1-3 (VTA) - D99-119 (VLU) Always Below 1 Ω
      t1-2 (E) - D99-96 (EVLU) Always Below 1 Ω
      t1-1 (VC) or D99-97 (VCVL) - Body ground Always 10 kΩ or higher
      t1-3 (VTA) or D99-119 (VLU) - Body ground Always 10 kΩ or higher

    4. Reconnect the throttle position sensor connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR Click here

    OK

  2. CHECK ECM TERMINAL VOLTAGE (VC TERMINAL)


    1. A003I8BE23
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Throttle Position Sensor)

      Disconnect the throttle position sensor connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      t1-1 (VC) - t1-2 (E) Ignition switch ON 4.5 to 5.5 V

    3. Reconnect the throttle position sensor connector.


    NG

    REPLACE ECM Click here

    OK

  3. REPLACE DIESEL THROTTLE BODY ASSEMBLY


    1. Replace the diesel throttle body assembly Click here.


    NEXT

  4. READ VALUE USING GTS


    1. Connect the GTS to the DLC3.

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

    3. Clear the DTCs Click here.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / Actual Throttle position.

    5. Check the movement of the throttle valve when idling the engine after starting it from ignition switch to ON.

      OK
      Condition GTS Display
      Ignition switch ON 95 to 105%
      Idling 5 to 15%

    NG

    REPLACE ECM Click here

    OK

    END

  5. REPLACE ECM


    1. Replace the ECM Click here.


    NEXT

    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED Click here

  6. REPAIR OR REPLACE HARNESS OR CONNECTOR


    1. Repair or replace the harness or connector.


    NEXT

  7. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED


    1. Connect the GTS to the DLC3.

    2. Clear the DTCs Click here.

    3. Turn the ignition switch off.

    4. Turn the ignition switch to ON for 3 seconds.

    5. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

    6. Confirm that the DTC is not output again.


    NEXT

    END