ECD SYSTEM, Diagnostic DTC:P0122 and P0123

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

DESCRIPTION

The ECM furnishes the 5-volt power and the ground connection for the throttle-valve actuator.

The ECM control unit opens and closes the throttle valve actuator electrically.

The exact current position of the throttle valve must be registered at all times in order to perform optimal control. This function is discharged by the throttle-valve sensor, which provides contactless monitoring of the throttle valve position within the throttle-valve actuator.

The electromotive throttle actuator is secured to the intake plenum.

A throttle valve is necessary for all diesel engines equipped with a particulate filter system. The throttle valve blocks the intake air to ensure that the necessary increased exhaust-gas temperatures required for regeneration of the particulate filter are reached.

The throttle-valve actuator closes when the ignition switch is turned off. This counteracts the tendency of the engine to vibrate during the shutdown phase. Another function is preventing the engine from overrevving.

When the ECD system detects increases in engine speed although no corresponding rises in the injection quantity have occurred, it responds by closing the throttle valve to limit engine speed.

A342520E01

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

P0122

Throttle/Pedal Position Sensor / Switch "A" Circuit Low

Throttle position sensor output (VTA1) is less than 0.15 V for 0.22 seconds.

(3 trip detection logic)

  • Throttle position sensor (diesel throttle body assembly)

  • Open or short in throttle position sensor circuit

  • ECM

Does not come on

DTC stored

P0123

Throttle / Pedal Position Sensor/Switch "A" Circuit High

Throttle position sensor output (VTA1) is more than 4.7 V for 0.22 seconds.

(3 trip detection logic)

  • Throttle position sensor (diesel throttle body assembly)

  • Open or short in throttle position sensor circuit

  • ECM

Does not come on

DTC stored
Table 1. Related Data List

DTC No.

Data List

P0122

P0123

  • Target Throttle Position

  • Actual Throttle Position

  • Throttle Sensor Volt %
Tip:

Throttle position sensor output voltage "Throttle Sensor Volt %" is converted using 5 V = 100 %.

WIRING DIAGRAM

A311418E03

CAUTION / NOTICE / HINT

Note:

When replacing the ECM, the ECM needs registration and initialization.

Click here

Tip:

  • When the ECM must be replaced, before replacing the ECM, perform the "Learning Values Save" function using the GTS. Then after installing the new ECM, perform all of the initialization/registrations 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

      X7-1 (VC) - B220-83 (VCTA)

      Always

      Below 1 Ω

      X7-3 (VTA) - B220-117 (VTA1)

      Always

      Below 1 Ω

      X7-2 (E2) - B220-81 (ETA)

      Always

      Below 1 Ω

      X7-1 (VC) or B220-83 (VCTA) - Body ground

      Always

      10 kΩ or higher

      X7-3 (VTA) or B220-117 (VTA1) - Body ground

      Always

      10 kΩ or higher

      X7-2 (E2) or B220-81 (ETA) - Body ground

      Always

      10 kΩ or higher

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTORClick here

    OK

  2. CHECK HARNESS AND CONNECTOR (VC VOLTAGE)

    1. A351163C03

      *a

      Front view of wire harness connector

      (to Diesel Throttle Body Assembly)

      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

      Switch Condition

      Specified Condition

      X7-1 (VC) - X7-2 (E2)

      Ignition switch ON

      4.5 to 5.5 V

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE ECMClick here

    OK

  3. REPLACE DIESEL THROTTLE BODY ASSEMBLY

    1. Replace diesel throttle body assembly.

      Click here

    Result

    Proceed to

    NEXT
    NEXT

  4. CHECK WHETHER DTC OUTPUT RECURS (DTC P0122 AND/OR P0123)

    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 60 seconds or more [A].

    5. Perform road test [B].

    6. Repeat [A] and [B] for the number of trips detected.

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

      Powertrain > Engine and ECT > Trouble Codes

    8. Read the DTCs.

      Result

      Result

      Proceed to

      No DTC output

      A

      DTC P0122 and/or P0123

      B
    A

    END

    B

  5. REPLACE ECM

    1. Replace the ECM.

      Click here

    Result

    Proceed to

    NEXT
    NEXT

    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIREDClick here

  6. REPAIR OR REPLACE HARNESS OR CONNECTOR

    1. Repair or replace the 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 60 seconds or more [A].

    5. Perform road test [B].

    6. Repeat [A] and [B] for the number of trips detected.

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

      Powertrain > Engine and ECT > Trouble Codes

    8. Confirm that the DTC is not output again.

    Result

    Proceed to

    NEXT
    NEXT

    END