Dtc P0120 Throttle / Pedal Position Sensor / Switch A Circuit

Engine. Lexus Is250, Is220D. Gse20 Ale20
2Ad-Fhv Engine Control System. Lexus Is250, Is220D. Gse20 Ale20

DESCRIPTION

MONITOR DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK HARNESS AND CONNECTOR (THROTTLE POSITION SENSOR - ECM)

CHECK TERMINAL VOLTAGE (VC TERMINAL OF THROTTLE POSITION SENSOR)

REPLACE DIESEL THROTTLE BODY ASSEMBLY

CHECK IF DTC OUTPUT RECURS

DTC P0120 Throttle / Pedal Position Sensor / Switch "A" Circuit

DTC P0122 Throttle / Pedal Position Sensor / Switch "A" Circuit Low Input

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


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

Lexus Is250, Is220D. Gse20 Ale20.2Ad-Fhv Engine Control System.Ecd System. Dtc P0120 Throttle / Pedal Position Sensor / Switch A Circuit


DTC No.
DTC Detection Condition
Trouble Area
-
Condition of DTC P0120, P0122, or P0123 continues for 0.5 seconds
(open or short in throttle position sensor circuit)
-
P0120
Throttle position sensor output (VLU) flutters up and down beyond normal operating range
(less than 0.2 V or more than 4.8 V)
(1 trip detection logic)
  1. Open or short in throttle valve position sensor circuit
  2. Throttle position sensor
  3. ECM
P0122
Throttle position sensor output (VLU) is less than 0.2 V
(1 trip detection logic)
  1. Throttle position sensor
  2. Open or short in VLU circuit
  3. Open in VC circuit
  4. ECM
P0123
Throttle position sensor output (VLU) is more than 4.8 V
(1 trip detection logic)
  1. Throttle position sensor
  2. Open in E2 circuit
  3. Short in VC and VLU circuits
  4. ECM

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.

Lexus Is250, Is220D. Gse20 Ale20.2Ad-Fhv Engine Control System.Ecd System. Dtc P0120 Throttle / Pedal Position Sensor / Switch A Circuit


WIRING DIAGRAM


Lexus Is250, Is220D. Gse20 Ale20.2Ad-Fhv Engine Control System.Ecd System. Dtc P0120 Throttle / Pedal Position Sensor / Switch A Circuit


INSPECTION PROCEDURE

NOTICE:
After replacing the ECM, the new ECM needs registration (Click here) and initialization (Click here).
HINT:
If DTCs relating to different systems are output, and they share terminal E2 as their ground, check this ground circuit first.
1.CHECK HARNESS AND CONNECTOR (THROTTLE POSITION SENSOR - ECM)


    Lexus Is250, Is220D. Gse20 Ale20.2Ad-Fhv Engine Control System.Ecd System. Dtc P0120 Throttle / Pedal Position Sensor / Switch A Circuit

  1. Disconnect the E59 ECM connectors.

  1. Disconnect the E61 throttle position sensor connector.

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

    Standard resistance:
    Tester Connection
    		Specified Condition
    VCVL (E59-73) - VC (E61-1)
    		Below 1 Ω
    VLU (E59-119) - VTA (E61-3)
    		Below 1 Ω
    EVLU (E59-96) - E2 (E61-2)
    		Below 1 Ω
    VCVL (E59-73) or VC (E61-1) - Body ground
    		10 kΩ or higher
    VLU (E59-119) or VTA (E61-3) - Body ground
    		10 kΩ or higher
    EVLU (E59-96) or E2 (E61-2) - Body ground
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


2.CHECK TERMINAL VOLTAGE (VC TERMINAL OF THROTTLE POSITION SENSOR)


    Lexus Is250, Is220D. Gse20 Ale20.2Ad-Fhv Engine Control System.Ecd System. Dtc P0120 Throttle / Pedal Position Sensor / Switch A Circuit

  1. Disconnect the E61 sensor connector.

  1. Turn the engine switch ON (IG).

  1. Measure the voltage.

    Standard voltage:
    Tester Connection
    		Specified Condition
    VC (E61-1) - E2 (E61-2)
    		4.5 to 5.5 V


NG
REPLACE ECM
OK


3.REPLACE DIESEL THROTTLE BODY ASSEMBLY

NEXT


4.CHECK IF DTC OUTPUT RECURS

  1. Clear the DTC(s) (Click here).

  1. Start the engine.

  1. Let the engine idle for 60 seconds.

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

  1. Check for DTC(s) (Click here).

    Result:

    Display (DTC Output)
    		Proceed to
    P0120, P0122 and/or P0123
    		A
    No output
    		B


B
END
A

REPLACE ECM