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

The throttle position sensor is mounted on the throttle with motor body assembly, and detects the opening angle of the throttle valve. This sensor is a non-contact type sensor. 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 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 VTA1 and VTA2 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.

Yaris. Ncp93, 131.1Nz-Fe Engine Control.Sfi System (For Sedan).
Dtc
P0120 Throttle / Pedal Position Sensor / Switch A Circuit Malfunction

DTC No.	DTC Detection Condition	Trouble Area
P0120	The output voltage of VTA1 quickly fluctuates beyond the lower and upper malfunction thresholds for 2 seconds or more (1 trip detection logic).	Throttle position sensor (built into throttle with motor body assembly) ECM
P0121	The difference between the VTA1 and VTA2 voltages is below 0.8 V or higher than 1.6 V for 2 seconds (1 trip detection logic).	Throttle position sensor (built into throttle with motor body assembly) Throttle position sensor circuit ECM
P0122	The output voltage of VTA1 is 0.2 V or less for 2 seconds or more (1 trip detection logic).	Throttle position sensor (built into throttle with motor body assembly) Short in VTA1 circuit Open in VC circuit ECM
P0123	The output voltage of VTA1 is 4.54 V or higher for 2 seconds or more (1 trip detection logic).	Throttle position sensor (built into throttle with motor body assembly) 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 or more (1 trip detection logic).	Throttle position sensor (built into throttle with motor body assembly) ECM
P0222	The output voltage of VTA2 is 1.75 V or less for 2 seconds or more (1 trip detection logic).	Throttle position sensor (built into throttle with motor body assembly) 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 or more (1 trip detection logic).	Throttle position sensor (built into throttle with motor body assembly) Open in VTA2 circuit Open in E2 circuit Short between VC and VTA2 circuits ECM
P2135	Either of the following conditions 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 Throttle position sensor (built into throttle with motor body assembly) ECM

HINT:

When any of these DTCs are output, check the throttle valve opening angle using the Techstream. Enter the following menus: Powertrain / Engine and ECT / Data List / 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)
Techstream Display	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 sensor to monitor the throttle valve opening angle. There are several checks that the ECM performs to confirm the proper operation of the throttle position sensor.

P0120, P0122, P0123, P0220, P0222, P0223, 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 circuit, 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 circuit, 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 circuit, and stores a DTC.

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

P0121:

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 the proper operation of the throttle position sensor and VTA1.
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 in 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.

MONITOR STRATEGY

Related DTCs	P0120: Throttle Position Sensor 1 Range Check (Fluctuating) P0121: Throttle Position Sensor Rationality P0122: Throttle Position Sensor 1 Range Check (Low Voltage) P0123: Throttle Position Sensor 1 Range Check (High Voltage) P0220: Throttle Position Sensor 2 Range Check (Fluctuating) P0222: Throttle Position Sensor 2 Range Check (Low Voltage) P0223: Throttle Position Sensor 2 Range Check (High Voltage) P2135: Throttle Position Sensor Range Check (Correlation)
Required Sensors/Components (Main)	Throttle position sensor
Required Sensors/Components (Related)	-
Frequency of Operation	Continuous
Duration	2 seconds: P0120, P0122, P0123, P0220, P0222 and P0223 Within 2 seconds: P0121 0.5 seconds: P2135 Case 1 0.4 seconds: P2135 Case 2
MIL Operation	Immediate
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

P0120, P0122, P0123, P0220, P0222, P0223, P2135
Monitor runs whenever following DTCs not present	None
Either of following conditions met	-
A. Ignition switch ON	0.012 seconds or more
B. Electronic throttle actuator power	ON

P0121
Monitor runs whenever following DTCs not present	None
Either of following conditions met	A or B
A. Ignition switch	ON
B. Electric throttle motor power	ON
Throttle position sensor circuit fail (P0120, P0122, P0123, P0220, P0222, P0223, P2135)	Not detected

TYPICAL MALFUNCTION THRESHOLDS

P0120
VTA1 voltage	0.2 V or less, or 4.54 V or higher

P0121
Either of following conditions met	-
Difference of learned throttle position sensor opener position voltage between VTA2 and VTA1	Higher than 1.6 V
Difference of learned throttle position sensor opener position voltage between VTA2 and VTA1	Below 0.8 V

P0122
VTA1 voltage	0.2 V or less

P0123
VTA1 voltage	4.54 V or higher

P0220
Either of following conditions met	-
A. VTA2 voltage	1.75 V or less
B. VTA2 voltage when VTA1 0.2 V or higher, and 2.02 V or less	4.8 V or higher

P0222
VTA2 voltage	1.75 V or less

P0223
VTA2 voltage when VTA1 0.2 V or higher, and 2.02 V or less	4.8 V or higher

P2135 Case 1
Difference between VTA1 and VTA2 voltages	0.02 V or less

P2135 Case 2
VTA1 voltage	0.2 V or less
VTA2 voltage	1.75 V or less

COMPONENT OPERATING RANGE

VTA1 voltage	More than 0.2 V, and less than 4.54 V
VTA2 voltage	More than 1.75 V, and less than 4.8 V

CONFIRMATION DRIVING PATTERN

Connect the Techstream to the DLC3.
Turn the ignition switch to ON and turn the Techstream on.
Clear DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON and turn the Techstream on [A].
Start the engine.
With the vehicle stationary, fully depress and release the accelerator pedal [B].
Idle the engine for 2 seconds or more [C].
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [D].
Read pending DTCs.
HINT:
1. If a pending DTC is output, the system is malfunctioning.
2. If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0120, P0121, P0122, P0123, P0220, P0222, P0223 or P2135.

Check the DTC judgment result.

Techstream Display	Description
NORMAL	DTC judgment completed System normal
ABNORMAL	DTC judgment completed System abnormal
INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions
N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

HINT:

If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
If the judgment result shows INCOMPLETE or N/A, perform steps [B] through [D] again.

If no pending DTC is output, perform a universal trip and check for permanent DTCs (YARIS_NCP93 RM000000PDK0T5X.html).
HINT:
1. If a permanent DTC is output, the system is malfunctioning.
2. If no permanent DTC is output, the system is normal.

FAIL-SAFE

When any of these DTCs or other DTCs relating to Electronic Throttle Control System (ETCS) 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 6.0° 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 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 ignition switch is then turned off.

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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 TECHSTREAM (THROTTLE POSITION SENSOR)

Connect the Techstream to the DLC3.

Turn the ignition switch to ON.

Turn the Techstream on.

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

Read the values displayed on the Techstream.

Result
When Accelerator Pedal Released		When Accelerator Pedal Depressed		Trouble Area	Proceed to
Throttle Position No. 1 (VTA1)	Throttle Position No. 2 (VTA2)	Throttle Position No. 1 (VTA1)	Throttle Position No. 2 (VTA2)	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
0 to 0.2 V, or 4.5 to 5.0 V	2.1 V to 3.1 V (Fail-safe)	0 to 0.2 V, or 4.5 to 5.0 V	2.1 V to 3.1 V (Fail-safe)	VTA1 circuit open or ground short
0.6 V to 1.4 V (Fail-safe)	0 to 0.2 V, or 4.5 to 5.0 V	0.6 V to 1.4 V (Fail-safe)	0 to 0.2 V, or 4.5 to 5.0 V	VTA2 circuit open or ground short
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)	Throttle position sensor circuit normal	B

HINT:

DTC P0121 is stored when the VTA1 and VTA2 output voltages are not consistent with the sensor characteristics. Therefore, check the freeze frame data when this DTC is stored. Use the following formula to confirm the relative differences in voltage.
Characteristic Sensor Output:
VTA2 x 0.8 is approximately equal to VTA1 + 1.11 V
VTA1: Throttle Position No. 1
VTA2: Throttle position No. 2
If DTC P0121 is output, proceed to "Check Harness And Connector (Throttle Position Sensor - ECM)".

Go to step 5

A

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

Disconnect the throttle with motor body assembly connector.

Disconnect the ECM connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
C53-5 (VC) - C51-115 (VCTA)	Always	Below 1 Ω
C53-6 (VTA) - C51-84 (VTA1)	Always	Below 1 Ω
C53-4 (VTA2) - C51-83 (VTA2)	Always	Below 1 Ω
C53-3 (E2) - C51-116 (ETA)	Always	Below 1 Ω
C53-5 (VC) or C51-115 (VCTA) - Body ground	Always	10 kΩ or higher
C53-6 (VTA) or C51-84 (VTA1) - Body ground	Always	10 kΩ or higher
C53-4 (VTA2) or C51-83 (VTA2) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.INSPECT ECM (VC VOLTAGE)

Disconnect the throttle with motor body 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
C53-5 (VC) - C53-3 (E2)
Ignition switch ON
4.5 to 5.5 V
Text in Illustration
*a
Front view of wire harness connector
(to Throttle with Motor Body Assembly)

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

REPLACE ECM (YARIS_NCP93 RM000001CN002IX.html)

OK

4.REPLACE THROTTLE WITH MOTOR BODY ASSEMBLY

Replace the throttle with motor body assembly (YARIS_NCP93 RM000003VHR00IX.html).
HINT:
Perform "Inspection After Repair" after replacing the throttle with motor body assembly (YARIS_NCP93 RM000004NJD006X.html).

NEXT

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

Connect the Techstream to the DLC3.

Turn the ignition switch to ON.

Turn the Techstream on.

Clear the DTCs (YARIS_NCP93 RM000000PDK0T5X.html).

Start the engine.

Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

Read DTCs.
Result
Result
Proceed to
DTC P0120, P0121, P0122, P0123, P0220, P0222, P0223 and/or P2135 are output
A
DTC is not output
B

Result
Result	Proceed to
DTC P0120, P0121, P0122, P0123, P0220, P0222, P0223 and/or P2135 are output	A
DTC is not output	B

END

REPLACE ECM (YARIS_NCP93 RM000001CN002IX.html)

Tester Connection	Switch Condition	Specified Condition
C53-5 (VC) - C53-3 (E2)	Ignition switch ON	4.5 to 5.5 V