ECD SYSTEM(w/ Glow Plug Controller), 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 built into the diesel throttle body 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 VTA1 of the ECM. The voltage applied to terminal VTA1 of the ECM increases in proportion to the opening angle of the throttle valve and becomes approximately 3.9 to 4.2 V when the throttle valve is fully opened.

The ECM determines the vehicle driving conditions from the signals input to its VTA1 terminal. This data is one of the inputs used for EGR control, etc.

B0044VRE02
*1 Magnet
*2 Hall IC
*3 Throttle Position Sensor
DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
P0122 Throttle / Pedal Position Sensor / Switch "A" Circuit Low Input

Throttle position sensor output (VTA1) is less than 0.2 V for 3 seconds.

(1 trip detection logic)

  • Throttle position sensor

  • Open or short in VTA1 circuit

  • Open in VCTA circuit

  • ECM

 Comes on DTC stored
P0123 Throttle / Pedal Position Sensor / Switch "A" Circuit High Input

Throttle position sensor output (VTA1) is higher than 4.8 V for 3 seconds.

(1 trip detection logic)

  • Throttle position sensor

  • Open in ETA circuit

  • VCTA and VTA1 circuits are short-circuited

  • ECM

 Comes on DTC stored
DTC Detection Drive Pattern
DTC No. DTC Detection Drive Pattern
P0122 Ignition switch ON
P0123
Related Data List
DTC No. Data List
P0122

  • Target Throttle Position

  • Actual Throttle Position

  • Throttle Sensor Volt %
P0123

Tech Tips


  • Throttle position sensor output voltage "Throttle Sensor Volt %" is converted using 5 V = 0 %.

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


    • Intake booming noise

    • Black smoke

    • Lack of power

    • Vibration at engine stop

    • Turbo overspeed, turbo damage

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.

B0042FHE05

WIRING DIAGRAM

B0042BKE01
*a Diesel Throttle Body Assembly

CAUTION / NOTICE / HINT

Note

When replacing the ECM, perform ECM Initialization and Registration.

Click here

Tech Tips


  • When the ECM must be replaced, before replacing the ECM, perform the "Learning Values Save" function using the GTS. Then after installing a new ECM, perform all of the initialization and registration procedures for the "Learning Values Write" function by following the instructions shown on the GTS display.

  • 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 diesel throttle body assembly 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
      B25-5 (VC) - B212-65 (VCTA) Always Below 1 Ω
      B25-6 (VTA) - B212-80 (VTA1) Always Below 1 Ω
      B25-3 (E2) - B212-112 (ETA) Always Below 1 Ω
      B25-5 (VC) or B212-65 (VCTA) - Body ground and other terminals Always 10 kΩ or higher
      B25-6 (VTA) or B212-80 (VTA1) - Body ground and other terminals Always 10 kΩ or higher
      B25-3 (E2) or B212-112 (ETA) - Body ground and other terminals Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR Click here

    OK

  2. CHECK TERMINAL VOLTAGE (VC VOLTAGE)

    B004419C02
    *a

    Front view of wire harness connector

    (to Diesel Throttle Body Assembly)

    1. Disconnect the diesel throttle body assembly connector.

    2. Turn the ignition switch to ON.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      B25-5 (VC) - B25-3 (E2) Ignition switch ON 4.5 to 5.5 V
      Result
      Proceed to
      OK
      NG

    NG

    GO TO STEP 5 Click here

    OK

  3. REPLACE DIESEL THROTTLE BODY ASSEMBLY


    1. Replace the diesel throttle body assembly.

      Click here

      Result
      Proceed to
      NEXT

    NEXT

  4. READ VALUE USING GTS (ACTUAL THROTTLE POSITION)


    1. Connect the GTS to the DLC3.

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

    3. Clear the DTCs.


      Powertrain > Engine and ECT > Clear DTCs

    4. Turn the ignition switch off and wait for 30 seconds or more.

    5. Start the engine and wait for 30 seconds or more.

    6. Enter the following menus: Powertrain / Engine and ECT / Data List / Actual Throttle Position.


      Powertrain > Engine and ECT > Data List
      Tester Display
      Actual Throttle Position

    7. Check the movement of the throttle valve when the ignition switch is turned off during engine idle.

      Tech Tips

      When read Data List values, confirm that PM regeneration is not activated (value of "After Injection Period" is 0) by entering the following menus: Powertrain / Engine and ECT / Data List / After Injection Period.

      If PM regeneration is activated (value of "After Injection Period" is not 0), drive the vehicle until the PM regeneration is complete (value of "After Injection Period" becomes 0).

      Standard
      Condition GTS Display
      Idling 10 to 100%
      Ignition switch off during engine idle Changes to 0% once, then returns to 100%
      Result
      Proceed to
      OK
      NG

    OK

    END

    NG

  5. REPLACE ECM


    1. Replace the ECM.

      Click here

      Result
      Proceed to
      NEXT

    NEXT

    GO TO STEP 7 Click here

  6. REPAIR OR REPLACE HARNESS OR CONNECTOR

    Result
    Proceed to
    NEXT

    NEXT

  7. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED


    1. Connect the GTS to the DLC3.

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

    3. Clear the DTCs.


      Powertrain > Engine and ECT > Clear DTCs

    4. Turn the ignition switch off and wait for 30 seconds or more.

    5. Start the engine and wait for 30 seconds or more.

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

    7. Confirm that the DTC is not output again.


      Powertrain > Engine and ECT > Trouble Codes
      Result
      Proceed to
      NEXT

    NEXT

    END