3Ur-Fe Engine Control. Dtc P0120 Throttle / Pedal Position Sensor / Switch A Circuit Malfunction

The TP sensor is mounted on the throttle body, 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 TP sensor has 2 sensor circuits, each of which transmits a signal, VTA1 and VTA2. VTA1 is used to detect the throttle valve 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 Vdj200.3Ur-Fe Engine Control.Sfi System.
Dtc
P0120 Throttle / Pedal Position Sensor / Switch A Circuit Malfunction

DTC Code	DTC Detection Condition	Trouble Area
P0120	The 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 (TP) sensor (built into throttle body) ECM
P0122	The output voltage of VTA1 is 0.2 V or less for 2 seconds when the accelerator pedal is depressed (1 trip detection logic).	TP sensor (built into throttle body) Short in VTA1 circuit Open in VC circuit ECM
P0123	The output voltage of VTA1 is 4.535 V or higher for 2 seconds when the accelerator pedal is depressed (1 trip detection logic).	TP sensor (built into throttle body) Open in VTA1 circuit Open in E2 circuit Short between VC and VTA1 circuits ECM
P0220	The 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).	TP sensor (built into throttle body) ECM
P0222	The output voltage of VTA2 is 1.75 V or less for 2 seconds when the accelerator pedal is depressed (1 trip detection logic).	TP sensor (built into throttle body) Short in VTA2 circuit Open in VC circuit ECM
P0223	The 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).	TP sensor (built into throttle body) Open in VTA2 circuit Open in E2 circuit Short between VC and VTA2 circuits ECM
P2135	Either condition (a) or (b) is met (1 trip detection logic): (a) The difference between the output voltages of VTA1 and VTA2 is 0.02 V or less for 0.5 seconds or more. (b) The output voltage of VTA1 is 0.2 V or less and VTA2 is 1.75 V or less for 0.4 seconds or more.	Short between VTA1 and VTA2 circuits TP sensor (built into throttle body) ECM

HINT:

When any of these DTCs is output, check the throttle valve opening angle by entering the following menus: Powertrain / Engine and ECT / Data List / ETCS / 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):

Display Item
Accelerator Pedal Fully Released
Accelerator Pedal Fully Depressed
Throttle Position No.1
0.5 to 1.1 V
3.2 to 4.8 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 (TP) sensor to monitor the throttle valve opening angle. There are several checks that the ECM performs to confirm the proper operation of the TP sensor.

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 DTC(s).

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 DTC(s).

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 DTC(s).

If the malfunction is not repaired successfully, a DTC is stored 10 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° throttle 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 opening angle, 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.
Fail-safe mode continues until a pass condition is detected, and the engine switch is then turned off.

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

These DTCs relate to the Throttle Position (TP) sensor.
Read freeze frame data using the intelligent tester. 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 INTELLIGENT TESTER (THROTTLE POSITION)

Connect the intelligent tester to the DLC3.

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

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

Check the values displayed on the tester.

Result
TP#1 (VTA1) When Accelerator Pedal Released	TP#2 (VTA2) When Accelerator Pedal Released	TP#1 (VTA1) When Accelerator Pedal Depressed	TP#2 (VTA2) When Accelerator Pedal Depressed	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	E2 circuit open	A
0 to 0.2 V, or 4.5 to 5.0 V	2.1 to 3.1 V (Fail-safe)	0 to 0.2 V, or 4.5 to 5.0 V	2.1 to 3.1 V (Fail-safe)	VTA1 circuit open or ground short	A
0.6 to 1.4 V (Fail-safe)	0 to 0.2 V, or 4.5 to 5.0 V	0.6 to 1.4 V (Fail-safe)	0 to 0.2 V, or 4.5 to 5.0 V	VTA2 circuit open or ground short	A
0.5 to 1.1 V	2.1 to 3.1 V	3.2 to 4.8 V (Not fail-safe)	4.6 to 5.0 V (Not fail-safe)	TP sensor circuit normal	B

HINT:

TP#1 stands for Throttle Position No. 1, and TP#2 stands for Throttle Position No. 2.

Go to step 5

A

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

Disconnect the C3 throttle body connector.

Disconnect the C45 ECM connector.

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

Standard Resistance:

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

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.INSPECT ECM (VC VOLTAGE)

Disconnect the C3 throttle body connector.

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)
Engine switch on (IG)
4.5 to 5.5 V

REPLACE ECM (Click here)

OK

4.REPLACE THROTTLE BODY ASSEMBLY

Replace the throttle body assembly (Click here).

NEXT

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

Connect the intelligent tester to the DLC3.

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

Clear DTCs (Click here).

Start the engine.

Allow the engine to idle for 15 seconds or more.

Enter the following menus: Powertrain / Engine and ECT / DTC.

Read DTCs.

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

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

SYSTEM OK

REPLACE ECM (Click here)

Display Item	Accelerator Pedal Fully Released	Accelerator Pedal Fully Depressed
Throttle Position No.1	0.5 to 1.1 V	3.2 to 4.8 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)	Engine switch on (IG)	4.5 to 5.5 V