Lexus IS250 IS220d GSE20 ALE20 4GR-FSE ENGINE CONTROL SYSTEM

DESCRIPTION

FAIL-SAFE

WIRING DIAGRAM

INSPECTION PROCEDURE

READ VALUE OF INTELLIGENT TESTER (ACCEL POS #1 AND ACCEL POS #2)

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

INSPECT ECM (VCPA AND VCP2 VOLTAGE)

REPLACE ACCELERATOR PEDAL ROD ASSEMBLY

CHECK WHETHER DTC OUTPUT RECURS (ACCELERATOR PEDAL POSITION SENSOR DTCS)

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

This ETCS (Electronic Throttle Control System) does not use a throttle cable.


The Accelerator Pedal Position (APP) sensor is mounted on the accelerator pedal bracket and has 2 sensor circuits: VPA (main) and VPA2 (sub). This sensor is a non-contact type, and uses Hall-effect elements, in order to yield accurate signals, even in extreme driving conditions, such as at high speeds as well as very low speeds. The voltage, which is applied to terminals VPA and VPA2 of the ECM, varies between 0 V and 5 V in proportion to the operating angle of the accelerator pedal (throttle valve). A signal from VPA indicates the actual accelerator pedal opening angle (throttle valve opening angle) and is used for engine control. A signal from VPA2 conveys the status of the VPA circuit and is used to check the APP sensor itself.


The ECM monitors the actual accelerator pedal opening angle (throttle valve opening angle) through the signals from VPA and VPA2, and controls the throttle actuator according to these signals.


Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit. 4GR-FSE ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

DTC No.DTC Detection ConditionTrouble Area
P2120VPA fluctuates rapidly beyond upper and lower malfunction thresholds for 0.5 seconds or more (1 trip detection logic)
Accelerator Pedal Position (APP) sensor
ECM
P2122VPA 0.4 V or less for 0.5 seconds or more when accelerator pedal fully released (1 trip detection logic)
APP sensor
Open in VCP1 circuit
Open or ground short in VPA circuit
ECM
P2123VPA 4.8 V or more for 2.0 seconds or more
(1 trip detection logic)
APP sensor
Open in EPA circuit
ECM
P2125VPA2 fluctuates rapidly beyond upper and lower malfunction thresholds for 0.5 seconds or more (1 trip detection logic)
APP sensor
ECM
P2127VPA2 1.2 V or less for 0.5 seconds or more when accelerator pedal fully released (1 trip detection logic)
APP sensor
Open in VCP2 circuit
Open or ground short in VPA2 circuit
ECM
P2128Conditions (a) and (b) continue for 2.0 seconds or more (1 trip detection logic):
(a) VPA2 4.8 V or more
(b) VPA between 0.4 V and 3.45 V
APP sensor
Open in EPA2 circuit
ECM
P2138Condition (a) or (b) continues for 2.0 seconds or more (1 trip detection logic):
(a) Difference between VPA and VPA2 0.02 V or less
(b) VPA 0.4 V or less and VPA2 1.2 V or less
Short between VPA and VPA2 circuits
APP sensor
ECM
  • HINT:
  • When any of these DTCs are set, check the APP sensor voltage by entering the following menus on the intelligent tester: Powertrain / Engine / Data List / Accelerator Position No. 1 and Accelerator Position No. 2.
Trouble AreasACCEL POS #1
When AP Released		ACCEL POS #2
When AP Released		ACCEL POS #1
When AP Depressed		ACCEL POS #2
When AP Depressed
VCP circuit open0 to 0.4 V 0 to 1.2 V 0 to 0.4 V 0 to 1.2 V
Open or ground short in VPA circuit0 to 0.4 V 1.2 to 2.0 V 0 to 0.4 V 3.4 to 5.0 V
Open or ground short in VPA2 circuit0.5 to 1.1 V 0 to 0.2 V 2.6 to 4.5 V 0 to 0.2 V
EPA circuit open4.5 to 5.0 V 4.5 to 5.0 V 4.5 to 5.0 V 4.5 to 5.0 V
Normal condition0.5 to 1.1 V 1.2 to 2.0 V 2.6 to 4.5 V 3.4 to 5.0 V
  • HINT:
Accelerator pedal positions are expressed as voltages.
AP denotes for Accelerator Pedal.

FAIL-SAFE

When any of DTCs P2120, P2121, P2122, P2123, P2125, P2127, P2128 and P2138 are set, the ECM enters fail-safe mode. If either of the 2 sensor circuits malfunctions, the ECM uses the remaining circuit to calculate the accelerator pedal position to allow the vehicle to continue driving. If both of the circuits malfunction, the ECM regards the accelerator pedal as being released. As a result, the throttle valve is closed and the engine idles.


Fail-safe mode continues until a pass condition is detected, and the engine switch is then turned to off.


WIRING DIAGRAM

Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit. 4GR-FSE ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

INSPECTION PROCEDURE

  • HINT:
Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions 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, if the air-fuel ratio was lean or rich, and other data, from the time the malfunction occurred .
These DTCs relate to the Accelerator Pedal Position (APP) sensor.
1.READ VALUE OF INTELLIGENT TESTER (ACCEL POS #1 AND ACCEL POS #2)
Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit. 4GR-FSE ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

Connect the intelligent tester to the DLC3.

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

Enter the following menus: Power train / Engine / Data List / Accelerator Position No. 1 and Accelerator Position No. 2.

Read the value displayed on the tester.

  • Standard voltage:
  • Accelerator Pedal OperationsACCEL POS #1
    (AP#1)    		ACCEL POS #2
    (AP#2)
    Released0.5 to 1.1 V1.2 to 2.0 V
    Depressed2.6 to 4.5 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. 4GR-FSE ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

Disconnect the A26 Accelerator Pedal Position (APP) sensor connector.

Disconnect the A6 ECM connector.

Measure the resistance of the wire harness side connector.

  • Standard resistance (Check for open):
  • Tester ConnectionSpecified Condition
    VPA (A26-6) - VPA (A6-33)Below 1 Ω
    EPA (A26-5) - EPA (A6-34)Below 1 Ω
    VCPA (A26-4) - VCPA (A6-35)Below 1 Ω
    VPA2 (A26-3) - VPA2 (A6-32)Below 1 Ω
    EPA2 (A26-2) - EPA2 (A6-26)Below 1 Ω
    VCP2 (A26-1) - VCP2 (A6-27)Below 1 Ω
  • Standard resistance (Check for short):
  • Tester ConnectionSpecified Condition
    VPA (A26-6) or VPA (A6-33) - body ground10 kΩ or higher
    EPA (A26-5) or EPA (A6-34) - body ground10 kΩ or higher
    VCPA (A26-4) or VCPA (A6-35) - body ground10 kΩ or higher
    VPA2 (A26-3) or VPA2 (A6-32) - body ground10 kΩ or higher
    EPA2 (A26-2) or EPA2 (A6-26) - body ground10 kΩ or higher
    VCP2 (A26-1) or VCP2 (A6-27) - body ground10 kΩ or higher

Reconnect the APP sensor connector.

Reconnect the ECM connector.

NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
3.INSPECT ECM (VCPA AND VCP2 VOLTAGE)
Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit. 4GR-FSE ENGINE CONTROL SYSTEM. Lexus IS250 IS220d GSE20 ALE20

Disconnect the A26 APP sensor connector.

Turn the engine switch on (IG).

Measure the voltage of the A6 ECM connector.

  • Standard voltage:
  • Tester ConnectionSpecified Condition
    VCPA (A6-35) - EPA (A6-34)4.5 to 5.0 V
    VCP2 (A6-27) - EPA2 (A6-26)4.5 to 5.0 V

Reconnect the APP sensor connector.

NG
REPLACE ECM
OK
4.REPLACE ACCELERATOR PEDAL ROD ASSEMBLY
NEXT
5.CHECK WHETHER DTC OUTPUT RECURS (ACCELERATOR PEDAL POSITION SENSOR DTCS)

Connect the intelligent tester to the DLC3.

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

Clear DTCs .

Start the engine.

Allow the engine to idle for 15 seconds.

Enter the following menus: Power train / Engine / DTC.

Read DTCs.

  • Result:
  • Display (DTC Output)Proceed to
    P2120, P2122, P2123, P2125, P2127, P2128, and/or P2138A
    No outputB
B
SYSTEM IS OK
A
REPLACE ECM
LEXUS IS250, IS220d / GSE20 ALE20
4GR-FSE ENGINE CONTROL SYSTEM
Lexus IS250 IS220d GSE20 ALE20
SFI SYSTEM