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

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

DESCRIPTION

Tech Tips


  • These troubleshooting procedures are for the throttle position sensor.

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

  • This throttle valve position sensor is a non-contact type.

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

The ECM judges the vehicle's driving conditions from the signals input to its VLU terminal. The data is one of the conditions for EGR control, etc.

A01E04ME03
DTC No. DTC Detection Condition Trouble Area
P0122

Throttle position sensor output (VLU) is less than 0.2 V

(1 trip detection logic)

  • Throttle position sensor

  • Open or short in VLU circuit

  • Open in VC circuit

  • ECM
P0123

Throttle position sensor output (VLU) is more than 4.8 V

(1 trip detection logic)

  • Throttle position sensor

  • Open in E2 circuit

  • VC and VLU circuits are short-circuited

  • ECM

MONITOR DESCRIPTION

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

A01E2GHE06

WIRING DIAGRAM

A01DVF6E02

INSPECTION PROCEDURE

Note

If the ECM is replaced, the new ECM needs registration Click here and initialization Click here.

Tech Tips


  • If DTCs related to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.

  • Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, and other data from the time the malfunction occurred.

PROCEDURE


  1. CHECK WIRE HARNESS (THROTTLE POSITION SENSOR - ECM)

    A01E0YJE17

    1. Disconnect the E7 and E8 ECM connectors.

    2. Disconnect the T2 throttle position sensor connector.

    3. Measure the resistance of the wire harness side connectors.

      Standard resistance (Check for open)
      Tester Connection Specified Condition
      E8-18 (VC) - T2-1 (VC) Below 1 Ω
      E7-29 (VLU) - T2-3 (VAF) Below 1 Ω
      E8-28 (E2) - T2-2 (E2) Below 1 Ω
      Standard resistance (Check for short)
      Tester Connection Specified Condition
      E8-18 (VC) or T2-1 (VC) - Body ground 10 kΩ or higher
      E7-29 (VLU) or T2-3 (VAF) - Body ground 10 kΩ or higher
      E8-28 (E2) or T2-2 (E2) - Body ground 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

  2. CHECK ECM (VC VOLTAGE)

    A01DZAPE05

    1. Disconnect the T2 throttle position sensor connector.

    2. Turn the ignition switch ON.

    3. Measure the voltage of the ECM connector.

      Standard voltage
      Tester Connection Specified Condition
      E8-18 (VC) - E8-28 (E2) 4.5 to 5.5 V

    NG

    REPLACE ECM

    OK

  3. REPLACE DIESEL THROTTLE BODY ASSEMBLY (THROTTLE VALVE)


    1. Replace diesel throttle body assembly Click here.


    NEXT

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


    1. Clear the DTC(s) Click here.

    2. Start the engine.

    3. Let the engine idle for 60 seconds.

    4. Repeat quick engine revving to 2,500 rpm for 30 seconds.

    5. Check for DTC(s).

      Result
      Display (DTC Output) Proceed to
      P0122 and/or P0123 A
      No output B

    B

    SYSTEM OK

    A

    REPLACE ECM