Lexus NX manuals

Lexus NX: Throttle Pedal Position Sensor / Switch "A" Circuit (P0120-P0123,P0220,P0222,P0223,P2135)

Lexus NX Service Manual / Engine & Hybrid System / 2ar-fxe (engine Control) / Sfi System / Throttle Pedal Position Sensor / Switch "A" Circuit (P0120-P0123,P0220,P0222,P0223,P2135)

DESCRIPTION

HINT:

These DTCs relate to the throttle position sensor.

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 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, VTA1 and VTA2 each of which transmits a signal. 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 a request from the hybrid system. These signals are also used in calculations such as air fuel ratio correction, power increase correction and fuel-cut control.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

P0120

Throttle Pedal Position Sensor / Switch "A" Circuit

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 (throttle body with motor assembly)
  • ECM

Comes on

DTC stored

P0121

Throttle Pedal Position Sensor / Switch "A" Circuit Range / Performance

The difference between the output voltages of VTA1 and VTA2 is less than 0.8 V, or higher than 1.6 V for 2 seconds (1 trip detection logic).
  • Throttle position sensor (throttle body with motor assembly)
  • Throttle position sensor circuit
  • ECM

Comes on

DTC stored

P0122

Throttle / Pedal Position Sensor / Switch "A" Circuit Low Input

The output voltage of VTA1 is 0.2 V or less for 2 seconds or more (1 trip detection logic).
  • Throttle position sensor (throttle body with motor assembly)
  • Short in VTA1 circuit
  • Open in VCTA circuit
  • ECM

Comes on

DTC stored

P0123

Throttle / Pedal Position Sensor / Switch "A" Circuit High Input

The output voltage of VTA1 is 4.535 V or higher for 2 seconds or more (1 trip detection logic).
  • Throttle position sensor (throttle body with motor assembly)
  • Open in VTA1 circuit
  • Open in ETA circuit
  • Short between VCTA and VTA1 circuits
  • ECM

Comes on

DTC stored

P0220

Throttle / Pedal Position Sensor / Switch "B" Circuit

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 (throttle body with motor assembly)
  • ECM

Comes on

DTC stored

P0222

Throttle / Pedal Position Sensor / Switch "B" Circuit Low Input

The output voltage of VTA2 is 1.75 V or less for 2 seconds or more (1 trip detection logic).
  • Throttle position sensor (throttle body with motor assembly)
  • Short in VTA2 circuit
  • Open in VCTA circuit
  • ECM

Comes on

DTC stored

P0223

Throttle / Pedal Position Sensor / Switch "B" Circuit High Input

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 (throttle body with motor assembly)
  • Open in VTA2 circuit
  • Open in ETA circuit
  • Short between VCTA and VTA2 circuits
  • ECM

Comes on

DTC stored

P2135

Throttle / Pedal Position Sensor / Switch "A" / "B" Voltage Correlation

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 (throttle body with motor assembly)
  • ECM

Comes on

DTC stored

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 / Gas Throttle / 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 4.98 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 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 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 in the sensor circuit, and stores a DTC.
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. In this case the ECM will illuminate the MIL and store this DTC.

MONITOR STRATEGY

Related DTCs

P0120: Throttle position sensor 1 range check (chattering)

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 (chattering)

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

All

Monitor runs whenever the following DTCs are not stored

None
P0120, P0122, P0123, P0220, P0222, P0223 and P2135

Either of the following conditions is met

A or B

A. Power switch off to on (IG)

0.012 seconds or more

B. Throttle actuator power

On
P0121

Either of the following conditions is met

A or B

A. Power switch

On (IG)

B. Throttle actuator 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 4.535 V or higher
P0121

Either of the following conditions is met

A or B

A. Difference of learned throttle position sensor opener position voltage between VTA2 and VTA1

Higher than 1.6 V

B. Difference of learned throttle position sensor opener position voltage between VTA2 and VTA1

Lower than 0.8 V
P0122

VTA1 voltage

0.2 V or less
P0123

VTA1 voltage

4.535 V or higher
P0220

Either of the following conditions is met

A or B

A. VTA2 voltage

1.75 V or less

B. VTA2 voltage when VTA1 0.2 V to 2.02 V

4.8 V or higher
P0222

VTA2 voltage

1.75 V or less
P0223

VTA2 voltage when VTA1 0.2 V to 2.02 V

4.8 V or higher
P2135 (Case 1)

Difference between VTA1 and VTA2 voltages

0.02 V or less
P2135 (Case 2)

Both of the following conditions are met

-

VTA1 voltage

0.2 V or less

VTA2 voltage

1.75 V or less

COMPONENT OPERATING RANGE

All of the following conditions are met

-

VTA1 voltage

Higher than 0.2 V, and less than 4.535 V

VTA2 voltage

Higher than 1.75 V, and less than 4.8 V

Difference between VTA1 and VTA2 voltages

Higher than 0.02 V

CONFIRMATION DRIVING PATTERN

  1. Connect the Techstream to the DLC3.
  2. Turn the power switch on (IG) and turn the Techstream on.
  3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
  4. Turn the power switch off and wait for at least 30 seconds.
  5. Turn the power switch on (IG) and turn the Techstream on [A].
  6. Put the engine in inspection mode (maintenance mode).

    Click here

  7. Start the engine.
  8. With the vehicle stationary, fully depress and release the accelerator pedal [B].
  9. Idle the engine for 2 seconds or more [C].
  10. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [D].
  11. Read the pending DTCs.

    HINT:

    • If a pending DTC is output, the system is malfunctioning.
    • If a pending DTC is not output, perform the following procedure.
  12. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
  13. Input the DTC: P0120, P0121, P0122, P0123, P0220, P0222, P0223 or P2135.
  14. 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.
  15. If no pending DTC is output, perform a universal trip and check for permanent DTCs.

    Click here

    HINT:

    • If a permanent DTC is output, the system is malfunctioning.
    • 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 5.5° throttle valve opening angle by the return spring. The ECM stops the engine and the vehicle can be driven using solely the hybrid system. 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 power switch is turned off.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

HINT:

  • DTC P0121 is stored when the VTA 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.

    Calculate the voltage of VTA and VTA2 according to Throttle Sensor Volt % and Throttle Sensor #2 Volt % respectively and confirm their consistency.

    Example:

    Throttle Sensor Volt % / 100 (%) x 5 (V) = Throttle Position No.1

    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

  • 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.

PROCEDURE

1.

CHECK HARNESS AND CONNECTOR (THROTTLE POSITION SENSOR - ECM)

(a) Disconnect the throttle body with motor assembly connector.

(b) Disconnect the ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

C2-5 (VC) - C48-125 (VCTA)

Always

Below 1 Ω

C2-6 (VTA) - C48-127 (VTA1)

Always

Below 1 Ω

C2-4 (VTA2) - C48-128 (VTA2)

Always

Below 1 Ω

C2-3 (E2) - C48-126 (ETA)

Always

Below 1 Ω

C2-5 (VC) or C48-125 (VCTA) - Body ground

Always

10 kΩ or higher

C2-6 (VTA) or C48-127 (VTA1) - Body ground

Always

10 kΩ or higher

C2-4 (VTA2) or C48-128 (VTA2) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

2.

INSPECT ECM (VC VOLTAGE)

*a

Front view of wire harness connector

(to Throttle Body with Motor Assembly)

(a) Disconnect the throttle body with motor assembly connector.

(b) Turn the power switch on (IG).

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

C2-5 (VC) - C2-3 (E2)

Power switch on (IG)

4.5 to 5.5 V
NG

REPLACE ECM

OK

3.

REPLACE THROTTLE BODY WITH MOTOR ASSEMBLY

(a) Replace the throttle body with motor assembly.

Click here

HINT:

Perform "Inspection After Repair" after replacing the throttle body with motor assembly.

Click here

NEXT

4.

CHECK WHETHER DTC OUTPUT RECURS (THROTTLE POSITION SENSOR DTCS)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Clear the DTCs.

Click here

Powertrain > Engine and ECT > Clear DTCs

(e) Turn the power switch off and wait for at least 30 seconds.

(f) Turn the power switch on (IG).

(g) Turn the Techstream on.

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

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

(j) Read the DTCs.

Powertrain > Engine and ECT > Trouble Codes

Result

Proceed to

DTC P0120, P0121, P0122, P0123, P0220, P0222, P0223, and/or P2135 are output

A

DTCs are not output

B
A

REPLACE ECM

B

END

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