1Gr-Fe Engine Control. Dtc P0120 Throttle / Pedal Position Sensor / Switch A Circuit Malfunction

The throttle position sensor is mounted on the throttle body with motor assembly and detects the opening angle of the throttle valve. This sensor is a non-contact type. It 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 throttle position sensor has 2 sensor circuits, each of which transmits a signal, VTA1 and VTA2. VTA1 is used to detect the throttle valve opening angle and VTA2 is used to detect malfunctions in VTA1. The sensor signal voltages vary between 0 V and 5 V in proportion to the throttle valve opening angle, and are transmitted to the VTA terminals of the ECM.
As the valve closes, the sensor output voltage decreases and as the valve opens, the sensor output voltage increases. The ECM calculates the throttle valve opening angle according to these signals and controls the throttle actuator in response to driver inputs. These signals are also used in calculations such as air-fuel ratio correction, power increase correction and fuel-cut control.

Land Cruiser. Urj200, 202 Grj200 Vdj200.1Gr-Fe Engine Control.Sfi System.
Dtc
P0120 Throttle / Pedal Position Sensor / Switch A Circuit Malfunction

DTC No.	DTC Detection Condition	Trouble Area
P0120	Output voltage of VTA1 quickly fluctuates beyond the lower and upper malfunction thresholds for 2 seconds when the accelerator pedal is depressed (1 trip detection logic).	Throttle position sensor (built into throttle body with motor assembly) ECM
P0121	Difference between VTA1 and VTA2 voltages is less than 0.8 V, or more than 1.6 V for 2 seconds (1 trip detection logic).	Throttle position sensor (built into throttle body with motor assembly) Throttle position sensor circuit ECM
P0122	Output voltage of VTA1 is 0.2 V or less for 2 seconds when the accelerator pedal is depressed (1 trip detection logic).	Throttle position sensor (built into throttle body with motor assembly) Short in VTA1 circuit Open in VC circuit ECM
P0123	Output voltage of VTA1 is 4.54 V or higher for 2 seconds when the accelerator pedal is depressed (1 trip detection logic).	Throttle position sensor (built into throttle body with motor assembly) Open in VTA1 circuit Open in ETA circuit Short between VC and VTA1 circuits ECM
P0220	Output voltage of VTA2 quickly fluctuates beyond the lower and upper malfunction thresholds for 2 seconds when the accelerator pedal is depressed (1 trip detection logic).	Throttle position sensor (built into throttle body with motor assembly) ECM
P0222	Output voltage of VTA2 is 1.75 V or less for 2 seconds when the accelerator pedal is depressed (1 trip detection logic).	Throttle position sensor (built into throttle body with motor assembly) Short in VTA2 circuit Open in VC circuit ECM
P0223	Output voltage of VTA2 is 4.8 V or higher, and VTA1 is between 0.2 V and 2.02 V for 2 seconds when the accelerator pedal is depressed (1 trip detection logic).	Throttle position sensor (built into throttle body with motor assembly) Open in VTA2 circuit Open in ETA circuit Short between VC and VTA2 circuits ECM
P2135	Either condition is met (1 trip detection logic): (a) Difference between the output voltages of VTA1 and VTA2 is 0.02 V or less for 0.5 seconds or more. (b) Output voltage of VTA1 is 0.2 V or less, and VTA2 is 1.75 V or less for 0.4 seconds or more.	Throttle position sensor (built into throttle body with motor assembly) Short between VTA1 and VTA2 circuits ECM

HINT:

When any of these DTCs is stored, check the throttle valve opening angle by entering the following menus: Powertrain / Engine and ECT / Data List / All Data / Throttle Position No.1 and Throttle Position No.2.

Throttle Position No.1 is the VTA1 signal, and Throttle Position No.2 is the VTA2 signal.

Reference (Normal Condition):

GTS Display
Accelerator Pedal Fully Released
Accelerator Pedal Fully Depressed
Throttle Position No.1
0.5 to 1.1 V
3.3 to 4.9 V
Throttle Position No.2
2.1 to 3.1 V
4.6 to 5.0 V

MONITOR DESCRIPTION

The ECM uses the throttle position sensor to monitor the throttle valve opening angle. There are several checks that the ECM performs to confirm that the throttle position sensor is operating properly.

P0120, P0122, P0123, P0220, P0222, P0223 and P2135

A specific voltage difference is expected between the sensor terminals, VTA1 and VTA2, for each throttle valve opening angle. If the difference between VTA1 and VTA2 is incorrect, the ECM interprets this as a malfunction in the sensor and stores a DTC.
VTA1 and VTA2 each have a specific voltage range. If VTA1 or VTA2 is outside the normal operating range, the ECM interprets this as a malfunction in the sensor and stores a DTC.
VTA1 and VTA2 should never be close to the same voltage level. If VTA1 is within 0.02 V of VTA2, the ECM determines that there is a short circuit in the sensor and stores a DTC.

If the malfunction is not repaired successfully, a DTC is stored 10 seconds after the engine is next started.

P0121

The ECM uses the throttle position sensor to monitor the throttle valve opening angle.
This sensor transmits two signals: VTA1 and VTA2. VTA1 is used to detect the throttle opening angle and VTA2 is used to detect malfunctions in VTA1. The ECM performs several checks to confirm that the throttle position sensor and VTA1 are operating properly.
For each throttle opening angle, a specific voltage difference is expected between the outputs of VTA1 and VTA2. If the output voltage difference between the two signals deviates from the normal operating range, the ECM interprets this as a malfunction of the throttle position sensor. The ECM illuminates the MIL and stores the DTC.
If the malfunction is not repaired successfully, the DTC is stored 2 seconds after the engine is next started.

FAIL-SAFE

When any of these DTCs as well as other DTCs relating to ETCS (Electronic Throttle Control System) malfunctions are stored, the ECM enters fail-safe mode. During fail-safe mode, the ECM cuts the current to the throttle actuator, and the throttle valve is returned to a 7° opening angle by the return spring. The ECM then adjusts the engine output by controlling the fuel injection (intermittent fuel-cut) and ignition timing in accordance with the accelerator pedal position to allow the vehicle to continue at a minimal speed. If the accelerator pedal is depressed firmly and gently, the vehicle can be driven slowly.
The ECM continues operating in fail-safe mode until a pass condition is detected and the ignition switch is turned off.

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

These DTCs relate to the throttle position sensor.
Read freeze frame data using the GTS. Freeze frame data records the engine condition 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.READ VALUE USING GTS (THROTTLE POSITION NO.1 AND NO.2)

Connect the GTS to the DLC3.

Turn the ignition switch to ON and turn the GTS on.

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

Check the values displayed on the GTS.

Result
When Accelerator Pedal Released		When Accelerator Pedal Depressed		Trouble Area	Proceed to
Throttle Position No.1	Throttle Position No.2	Throttle Position No.1	Throttle Position No.2	Trouble Area	Proceed to
0 to 0.2 V	0 to 0.2 V	0 to 0.2 V	0 to 0.2 V	VC circuit open	A
4.5 to 5.0 V	4.5 to 5.0 V	4.5 to 5.0 V	4.5 to 5.0 V	ETA circuit open
0 to 0.2 V, or 4.5 to 5.0 V	2.4 to 3.4 V (Fail-safe)	0 to 0.2 V, or 4.5 to 5.0 V	2.4 to 3.4 V (Fail-safe)	VTA1 circuit open or shorted to ground
0.7 to 1.3 V (Fail-safe)	0 to 0.2 V, or 4.5 to 5.0 V	0.7 to 1.3 V (Fail-safe)	0 to 0.2 V, or 4.5 to 5.0 V	VTA2 circuit open or shorted to ground
0.5 to 1.1 V	2.1 to 3.1 V	3.3 to 4.9 V (Not fail-safe)	4.6 to 5.0 V (Not fail-safe)	TP sensor circuit normal	B

Go to step 5

A

2.CHECK HARNESS AND CONNECTOR (THROTTLE POSITION SENSOR - ECM)

Disconnect the throttle body with motor assembly connector.

Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance:

for LHD
Tester Connection	Condition	Specified Condition
C3-5 (VC) - C45-80 (VCTA)	Always	Below 1 Ω
C3-6 (VTA) - C45-78 (VTA1)	Always	Below 1 Ω
C3-4 (VTA2) - C45-77 (VTA2)	Always	Below 1 Ω
C3-3 (E2) - C45-79 (ETA)	Always	Below 1 Ω
C3-5 (VC) or C45-80 (VCTA) - Body ground	Always	10 kΩ or higher
C3-6 (VTA) or C45-78 (VTA1) - Body ground	Always	10 kΩ or higher
C3-4 (VTA2) or C45-77 (VTA2) - Body ground	Always	10 kΩ or higher

for RHD
Tester Connection	Condition	Specified Condition
C3-5 (VC) - C46-80 (VCTA)	Always	Below 1 Ω
C3-6 (VTA) - C46-78 (VTA1)	Always	Below 1 Ω
C3-4 (VTA2) - C46-77 (VTA2)	Always	Below 1 Ω
C3-3 (E2) - C46-79 (ETA)	Always	Below 1 Ω
C3-5 (VC) or C46-80 (VCTA) - Body ground	Always	10 kΩ or higher
C3-6 (VTA) or C46-78 (VTA1) - Body ground	Always	10 kΩ or higher
C3-4 (VTA2) or C46-77 (VTA2) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.INSPECT ECM (VC VOLTAGE)

Disconnect the throttle body with motor assembly connector.

Turn the ignition switch to ON.

Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Tester Connection
Switch Condition
Specified Condition
C3-5 (VC) - C3-3 (E2)
Ignition switch ON
4.5 to 5.5 V
Text in Illustration
*a
Front view of wire harness connector
(to Throttle Body with Motor Assembly)

Text in Illustration
*a	Front view of wire harness connector (to Throttle Body with Motor Assembly)

REPLACE ECM (Click here)

OK

4.REPLACE THROTTLE BODY WITH MOTOR ASSEMBLY

Replace the throttle body with motor assembly (Click here).

NEXT

5.CHECK WHETHER DTC OUTPUT RECURS (THROTTLE POSITION SENSOR DTCS)

Connect the GTS to the DLC3.

Turn the ignition switch to ON and turn the GTS on.

Clear the DTCs (Click here).

Start the engine.

Allow the engine to idle for 15 seconds or more.

Read the output DTCs.

Result
Result
Proceed to
P0120, P0121, P0122, P0123, P0220, P0222, P0223 and/or P2135 is output
A
No DTC is output
B

Result
Result	Proceed to
P0120, P0121, P0122, P0123, P0220, P0222, P0223 and/or P2135 is output	A
No DTC is output	B

SYSTEM OK

REPLACE ECM (Click here)

GTS Display	Accelerator Pedal Fully Released	Accelerator Pedal Fully Depressed
Throttle Position No.1	0.5 to 1.1 V	3.3 to 4.9 V
Throttle Position No.2	2.1 to 3.1 V	4.6 to 5.0 V

Tester Connection	Switch Condition	Specified Condition
C3-5 (VC) - C3-3 (E2)	Ignition switch ON	4.5 to 5.5 V