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ECD SYSTEM, Diagnostic DTC:P0122, P0123

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

The throttle position sensor is mounted on 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 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 data is used for EGR control, etc.

Table 1. P0122
DTC Detection Drive Pattern DTC Detection Condition Trouble Area
Ignition switch ON for 3 seconds

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

(1 trip detection logic)

  • Throttle position sensor

  • Open or short in VLU circuit

  • Open in VC circuit

  • ECM
Table 2. P0123
DTC Detection Drive Pattern DTC Detection Condition Trouble Area
Ignition switch ON for 3 seconds

Throttle position sensor output (VLU) is more 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
Table 3. Related Data List
DTC No. Data List
P0122 Throttle Sensor Volt %
P0123
Tip:

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

  • When fully closed: 14% or less.

  • When fully open: 70% or more.

  • When the ignition switch is turned from off to ON, the throttle valve fully opens once.

  • When the ignition switch is turned from ON to off, the throttle valve fully closes once.


  • If DTC P0122 and/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

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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.

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WIRING DIAGRAM

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INSPECTION PROCEDURE

Note:

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

Tip:

Read freeze frame data using the intelligent tester. 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.

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PROCEDURE


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    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 (Check for Open)
      Tester Connection Condition Specified Condition
      C9-5 (VC) - C69-97 (VCVL) Always Below 1 Ω
      C9-6 (VTA) - C69-119 (VLU) Always Below 1 Ω
      C9-3 (E2) - C69-96 (EVLU) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      C9-5 (VC) or C69-97 (VCVL) - Body ground Always 10 kΩ or higher
      C9-6 (VTA) or C69-119 (VLU) - Body ground Always 10 kΩ or higher
      C9-3 (E2) or C69-96 (EVLU) - Body ground Always 10 kΩ or higher
      Table 4. Text in Illustration
      *1

      Front view of wire harness connector

      (to Throttle Body)
      *2

      Front view of wire harness connector

      (to ECM)

    4. Reconnect the diesel throttle body assembly connector.

    5. Reconnect the ECM connector.


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    CHECK ECM TERMINAL VOLTAGE (VC TERMINAL)


    1. A01IR07E02

      Disconnect the diesel throttle body assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      C9-5 (VC) - C9-3 (E2) Ignition switch ON 4.98 to 5.02 V
      Table 5. Text in Illustration
      *1

      Front view of wire harness connector

      (to Throttle Body)

    3. Reconnect the diesel throttle body assembly connector.


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    REPLACE DIESEL THROTTLE BODY ASSEMBLY


    1. Replace the diesel throttle body assembly (Click here).


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    CHECK WHETHER DTC OUTPUT RECURS


    1. Connect the intelligent tester to the DLC3.

    2. Clear the DTCs (Click here).

    3. Turn the ignition switch off for 30 seconds or more.

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

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

    6. Read the DTCs.

      Table 6. Result
      Result Proceed to
      P0122 or P0123 A
      No output B

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    REPLACE ECM


    1. Replace the ECM (Click here).


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    REPAIR OR REPLACE HARNESS OR CONNECTOR


    1. Repair or replace the harness or connector.


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    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED


    1. Connect the intelligent tester to the DLC3.

    2. Clear the DTCs (Click here).

    3. Turn the ignition switch off for 30 seconds or more.

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

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

    6. Confirm that the DTC is not output again.


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    END