Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit

Engine. Lexus Gs430, Gs300. Uzs190 Grs190
3Uz-Fe Engine Control System. Lexus Gs430, Gs300. Uzs190 Grs190

DESCRIPTION

MONITOR DESCRIPTION

FAIL-SAFE

WIRING DIAGRAM

INSPECTION PROCEDURE

READ DATA LIST (ACCEL POS #1 AND ACCEL POS #2)

CHECK WIRE HARNESS (ACCELERATOR PEDAL POSITION SENSOR - ECM)

CHECK ECM (VPA, VPA2 VOLTAGE)

REPLACE ACCELERATOR PEDAL

READ OUTPUT DTC (ACCELERATOR PEDAL POSITION SENSOR DTCS ARE OUTPUT AGAIN)

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:
  1. The Electronic Throttle Control System (ETCS) does not use a throttle cable.
  2. The accelerator pedal position sensor is a non-contact type.
  3. The ETCS does not use a throttle cable.
    The accelerator pedal position sensor is mounted on the accelerator pedal bracket and has 2 sensor circuits: VPA (main) and VPA2 (sub). This sensor uses Hall-effect elements to yield accurate signals, even in extreme driving conditions, such as at high speeds as well as at 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 accelerator pedal position 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.

Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System. Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit


DTC No.
DTC Detection Conditions
Trouble Areas
P2120
VPA fluctuates rapidly beyond upper and lower malfunction thresholds for 0.5 seconds or more (1 trip detection logic)
  1. Accelerator pedal position sensor
  1. ECM
P2122
VPA 0.4 V or less for 0.5 seconds or more when accelerator pedal fully released (1 trip detection logic)
  1. Accelerator pedal position sensor
  1. Open in VCP1 circuit
  1. Open or ground short in VPA circuit
  1. ECM
P2123
VPA 4.8 V or more for 2.0 seconds or more
(1 trip detection logic)
  1. Accelerator pedal position sensor
  1. Open in EPA circuit
  1. ECM
P2125
VPA2 fluctuates rapidly beyond upper and lower malfunction thresholds for 0.5 seconds or more (1 trip detection logic)
  1. Accelerator pedal position sensor
  1. ECM
P2127
VPA2 1.2 V or less for 0.5 seconds or more when accelerator pedal fully released (1 trip detection logic)
  1. Accelerator pedal position sensor
  1. Open in VCP2 circuit
  1. Open or ground short in VPA2 circuit
  1. ECM
P2128
Conditions (a) and (b) continue for 2.0 seconds or more (1 trip detection logic):
(a) VPA2 4.8 V or more
(b) VPA between 0.2 V and 3.45 V
  1. Accelerator pedal position sensor
  1. Open in EPA2 circuit
  1. ECM
P2138
Condition (a) or (b) continues for 2.0 seconds or more (1 trip detection logic):
(a) Difference between VPA and VPA2 is 0.02 V or less
(b) VPA is 0.2 V or less and VPA2 is 0.5 V or less
  1. Short between VPA and VPA2 circuits
  1. Accelerator pedal position sensor
  1. ECM

HINT:
When any of these DTCs are set, check the accelerator pedal position sensor voltage by entering the following menus on the intelligent tester: Powertrain / Engine / Data List / Primary / Accelerator Position No. 1 and Accelerator Position No. 2.

Trouble Areas
Accelerator Position No. 1
When AP Released
Accelerator Position No. 2
When AP Released
Accelerator Position No. 1
When AP Depressed
Accelerator Position No. 2
When AP Depressed
VCP circuit open
0 to 0.2 V
0 to 0.2 V
0 to 0.2 V
0 to 0.2 V
Open or ground short in VPA circuit
0 to 0.2 V
1.2 to 2.0 V
0 to 0.2 V
3.4 to 5.0 V
Open or ground short in VPA2 circuit
0.5 to 1.1 V
0 to 0.2 V
2.6 to 4.5 V
0 to 0.2 V
EPA circuit open
4.5 to 5.0 V
4.5 to 5.0 V
4.5 to 5.0 V
4.5 to 5.0 V
Normal condition
0.5 to 1.1 V
1.2 to 2.0 V
2.6 to 4.5 V
3.4 to 5.0 V
HINT:
  1. Accelerator pedal positions are expressed as voltages.
  1. AP stands for Accelerator Pedal.

MONITOR DESCRIPTION

When either of the output voltage of VPA or VPA2 deviates from the standard range, or the difference between the output voltage of the 2 sensor circuits is less than the threshold, the ECM determines that there is a malfunction in the accelerator pedal position sensor. The ECM then illuminates the MIL and sets a DTC.
Example:
When the output voltage of VPA drops below 0.2 V for more than 0.5 seconds when the accelerator pedal is fully depressed, DTC P2122 is set.
If the malfunction is not repaired successfully, a DTC is set 2 seconds after the engine is started again.

FAIL-SAFE

When any of DTCs P2120, P2121, P2122, P2123, P2125, P2127, P2128 and P2138 is 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 turns the engine switch off.

WIRING DIAGRAM


Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System. Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit


INSPECTION PROCEDURE

HINT:
  1. 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.
  1. These DTCs relate to the accelerator pedal position sensor.
1.READ DATA LIST (ACCEL POS #1 AND ACCEL POS #2)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System. Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit

  1. Connect the intelligent tester to the DLC3.

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

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

  1. Read the value.

    Standard voltage:
    Accelerator Pedal Operations
    		Accelerator Position No. 1
    		Accelerator Position No. 2
    Released
    		0.5 to 1.1 V
    		1.2 to 2.0 V
    Depressed
    		2.6 to 4.5 V
    		3.4 to 5.0 V


OK
Go to step 5
NG


2.CHECK WIRE HARNESS (ACCELERATOR PEDAL POSITION SENSOR - ECM)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System. Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit

  1. Disconnect the A36 accelerator pedal position sensor connector.

  1. Disconnect the A7 ECM connector.

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

    Standard resistance:
    Tester Connections
    		Specified Conditions
    A36-1 (VCP2) - A7-27 (VCP2)
    		Below 1 Ω
    A36-2 (EPA2) - A7-26 (EPA2)
    		Below 1 Ω
    A36-3 (VPA2) - A7-32 (VPA2)
    		Below 1 Ω
    A36-4 (VCPA) - A7-35 (VCPA)
    		Below 1 Ω
    A36-5 (EPA) - A7-34 (EPA)
    		Below 1 Ω
    A36-6 (VPA) - A7-33 (VPA)
    		Below 1 Ω
    A36-1 (VCP2) or A7-27 (VCP2) - Body ground
    		10 kΩ or higher
    A36-2 (EPA2) or A7-26 (EPA2) - Body ground
    		10 kΩ or higher
    A36-3 (VPA2) or A7-32 (VPA2) - Body ground
    		10 kΩ or higher
    A36-4 (VCPA) or A7-35 (VCPA) - Body ground
    		10 kΩ or higher
    A36-5 (EPA) or A7-34 (EPA) - Body ground
    		10 kΩ or higher
    A36-6 (VPA) or A7-33 (VPA) - Body ground
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK


3.CHECK ECM (VPA, VPA2 VOLTAGE)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System. Dtc P2120 Throttle / Pedal Position Sensor / Switch D Circuit

  1. Disconnect the A36 accelerator pedal position sensor connector.

  1. Turn the engine switch on (IG).

  1. Measure the voltage of the ECM.

    Standard voltage:
    Tester Connections
    		Specified Conditions
    A7-33 (VPA) - A7-34 (EPA)
    		4.5 to 5.0 V
    A7-32 (VPA2) - A7-26 (EPA2)
    		4.5 to 5.0 V


NG
REPLACE ECM
OK


4.REPLACE ACCELERATOR PEDAL

NEXT


5.READ OUTPUT DTC (ACCELERATOR PEDAL POSITION SENSOR DTCS ARE OUTPUT AGAIN)

  1. Clear the DTCs (Click here).

  1. Start the engine and allow the engine to idle for 15 seconds or more.

  1. Read DTCs.

    Result:

    Display (DTC output)
    		Proceed to
    P2120, P2122, P2123, P2125, P2127, P2128, and/or P2138
    		A
    No output
    		B


B
SYSTEM OK
A

REPLACE ECM