Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit

Lexus IS250 IS220d GSE20 ALE20 2AD-FHV ENGINE CONTROL SYSTEM

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

READ VALUE OF INTELLIGENT TESTER (ACCELERATOR PEDAL POSITION SENSOR VALUE)

CHECK HARNESS AND CONNECTOR (ACCELERATOR PEDAL POSITION SENSOR - ECM)

INSPECT ECM TERMINAL VOLTAGE (VCPA AND VCP2 TERMINALS)

REPLACE ACCELERATOR PEDAL ROD ASSEMBLY

CHECK IF OUTPUT DTC RECURS

DTC P2120 Throttle / Pedal Position Sensor / Switch "D" Circuit

DTC P2122 Throttle / Pedal Position Sensor / Switch "D" Circuit Low Input

DTC P2123 Throttle / Pedal Position Sensor / Switch "D" Circuit High Input

DTC P2125 Throttle / Pedal Position Sensor / Switch "E" Circuit

DTC P2127 Throttle / Pedal Position Sensor / Switch "E" Circuit Low Input

DTC P2128 Throttle / Pedal Position Sensor / Switch "E" Circuit High Input

DTC P2138 Throttle / Pedal Position Sensor / Switch "D" / "E" Voltage Correlation

DESCRIPTION

  • HINT:
This is the repair procedure for the accelerator pedal position sensor.
This electrical throttle system does not use a throttle cable.
This accelerator pedal position sensor is a non-contact type.

The accelerator pedal position sensor is mounted on the accelerator pedal and detects the opening angle of the accelerator pedal. Since this sensor is electronically controlled with Hall-effect elements, accurate control and reliability can be obtained. It has 2 sensors to detect the accelerator position and a malfunction of the accelerator position sensor.


In the accelerator pedal position sensor, the voltage applied to pedal terminals VPA and VPA2 of the ECM changes between 0 V and 5 V in proportion to the opening angle of the accelerator pedal. The VPA is a signal to indicate the actual accelerator pedal opening angle which is used for the engine control, and the VPA2 is a signal to indicate the information about the opening angle which is used for detecting malfunctions. The ECM judges the current opening angle of the accelerator pedal using signals from terminals VPA and VPA2, and the ECM controls the throttle motor based on these signals.


Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit. 2AD-FHV ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

DTC No.DTC Detection Condition
(All of following are 1 trip detection logic)		Trouble Area
P2120 Condition (a) or (b) continues for 0.5 sec. or more:
(a) VPA is 0.4 V or less
(b) VPA is 4.8 V or more
Accelerator pedal position sensor
Accelerator pedal
Accelerator pedal rod (arm) deformed
ECM
P2122 VPA is 0.4 V or less for 0.5 sec. or more when VPA2 output indicates that accelerator pedal is depressed
Accelerator pedal position sensor
Open in VCPA circuit
VPA circuit open or ground short
Accelerator pedal
Accelerator pedal rod (arm) deformed
ECM
P2123 Condition (a) continues for 2.0 sec. or more:
(a) VPA is 4.8 V or more
Accelerator pedal position sensor
Open in EPA circuit
Accelerator pedal
Accelerator pedal rod (arm) deformed
ECM
P2125 Condition (a) or (b) continues for 0.5 sec. or more:
(a) VPA2 is 1.2 V or less
(b) VPA2 is 4.8 V or more
Accelerator pedal position sensor
Accelerator pedal
Accelerator pedal rod (arm) deformed
ECM
P2127 VPA2 is 1.2 V or less for 0.5 sec. or more when VPA output indicates accelerator pedal is opened
Accelerator pedal position sensor
Open in VCP2 circuit
VPA2 circuit open or ground short
Accelerator pedal
Accelerator pedal rod (arm) deformed
ECM
P2128 Conditions (a) and (b) continue for 2.0 sec. or more:
(a) VPA2 is 4.8 V or more
(b) VPA is 0.4 V or more and VPA is 3.45 V or less
Accelerator pedal position sensor
Open in EPA2 circuit
Accelerator pedal
Accelerator pedal rod (arm) deformed
ECM
P2138 Condition (a) or (b) continues for 2.0 sec. or more:
(a) Difference between VPA and VPA2 is 0.02 V or less
(b) VPA is 0.4 V or less and VPA2 is 1.2 V or less
VPA and VPA2 circuits are short circuited
Accelerator pedal position sensor
Accelerator pedal
Accelerator pedal rod (arm) deformed
ECM
  • HINT:
  • When DTC P2120, P2122, P2123, P2125, P2127, P2128, or P2138 is detected, check the output voltage of the accelerator pedal position sensor by entering the following menus on the intelligent tester: Powertrain / Engine / Data List / Accel Position 1 and Accel Position 2.
-Accelerator pedal position expressed as voltage outputAccelerator pedal position expressed as voltage outputAccelerator pedal position expressed as voltage outputAccelerator pedal position expressed as voltage output
-Accelerator pedal releasedAccelerator pedal releasedAccelerator pedal depressedAccelerator pedal depressed
Trouble AreaAccelerator Position No. 1Accelerator Position No. 2Accelerator Position No. 1Accelerator Position No. 2
VCP circuit open0 to 0.2 V0 to 0.2 V0 to 0.2 V0 to 0.2 V
VPA circuit open or ground short0 to 0.2 V0.9 to 2.3 V0 to 0.2 V3.4 to 5.0 V
VPA2 circuit open or ground short0.5 to 1.1 V0 to 0.2 V3.0 to 4.6 V0 to 0.2 V
EP circuit open4.5 to 5.0 V4.5 to 5.0 V4.5 to 5.0 V4.5 to 5.0 V

WIRING DIAGRAM

Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit. 2AD-FHV ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

INSPECTION PROCEDURE

  • NOTICE:
  • After replacing the ECM, the new ECM needs registration and initialization .
1.READ VALUE OF INTELLIGENT TESTER (ACCELERATOR PEDAL POSITION SENSOR VALUE)
Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit. 2AD-FHV ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

Connect the intelligent tester to the DLC3.

Turn the engine switch ON (IG) and turn the intelligent tester ON.

Enter the following menus: Powertrain / Engine / Data List / Accel Position 1 and Accel Position 2.

Read the values.

  • Standard voltage:
  • Accelerator PedalAccel Position 1Accel Position 2
    Released0.5 to 1.1 V0.9 to 2.3 V
    Depressed3.0 to 4.6 V3.4 to 5.0 V
OK
Go to step 5
NG
2.CHECK HARNESS AND CONNECTOR (ACCELERATOR PEDAL POSITION SENSOR - ECM)
Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit. 2AD-FHV ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

Disconnect the A26 sensor connector.

Disconnect the A49 ECM connector.

Measure the resistance of the wire harness side connectors.

  • Standard resistance:
  • Tester ConnectionSpecified Condition
    VCP2 (A26-1) - VCP2 (A49-56)Below 1 Ω
    EPA2 (A26-2) - EPA2 (A49-58)Below 1 Ω
    VPA2 (A26-3) - VPA2 (A49-54)Below 1 Ω
    VCPA (A26-4) - VCPA (A49-55)Below 1 Ω
    EPA (A26-5) - EPA (A49-57)Below 1 Ω
    VPA (A26-6) - VPA (A49-53)Below 1 Ω
    VCP2 (A26-1) or VCP2 (A49-56) - Body ground10 kΩ or higher
    EPA2 (A26-2) or EPA2 (A49-58) - Body ground10 kΩ or higher
    VPA2 (A26-3) or VPA2 (A49-54) - Body ground10 kΩ or higher
    VCPA (A26-4) or VCPA (A49-55) - Body ground10 kΩ or higher
    EPA (A26-5) or EPA (A49-57) - Body ground10 kΩ or higher
    VPA (A26-6) or VPA (A49-53) - Body ground10 kΩ or higher
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
3.INSPECT ECM TERMINAL VOLTAGE (VCPA AND VCP2 TERMINALS)
Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit. 2AD-FHV ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

Disconnect the A26 sensor connector.

Turn the engine switch ON (IG).

Measure the voltage of the sensor connector.

  • Standard voltage:
  • Tester ConnectionSpecified Condition
    VCPA (A26-4) - EPA (A26-5)4.5 to 5.5 V
    VCP2 (A26-1) - EPA2 (A26-2)
NG
REPLACE ECM
OK
4.REPLACE ACCELERATOR PEDAL ROD ASSEMBLY
NEXT
5.CHECK IF OUTPUT DTC RECURS

Clear the DTC .

Start the engine.

Drive the engine at idle for 15 seconds or more.

Read the DTC .

  • Result:
  • Display (DTC output)Proceed to
    P2120, P2122, P2123, P2125, P2127, P2128, or P2138 is output againA
    P2120, P2122, P2123, P2125, P2127, P2128, or P2138 is not outputB
B
END
A
REPLACE ECM