Lexus ES manuals

Lexus ES: Throttle / Pedal Position Sensor / Switch "A" Circuit Short to Ground (P012011)

Lexus ES (XZ10) Service Manual / Engine & Hybrid System / 2gr-fks (engine Control) / Sfi System / Throttle / Pedal Position Sensor / Switch "A" Circuit Short to Ground (P012011)

DESCRIPTION

The throttle position sensor is built into 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 driver inputs. These signals are also used in calculations such as air fuel ratio correction, power increase correction and fuel-cut control.

HINT:

  • When throttle position sensor DTCs are output, check the throttle valve opening angle using the Techstream. Enter the following menus: Powertrain / Engine / Data List / Throttle Position Sensor No.1 Voltage and Throttle Position Sensor No.2 Voltage.
  • Throttle Position Sensor No.1 Voltage is the VTA1 signal, and Throttle Position Sensor No.2 Voltage is the VTA2 signal.

    Reference (Normal Condition):

    When Accelerator Pedal Fully Released

    When Accelerator Pedal Fully Depressed

    (Engine Running)

    Throttle Position Sensor No.1 Voltage (VTA1)

    Throttle Position Sensor No.2 Voltage (VTA2)

    Throttle Position Sensor No.1 Voltage (VTA1)

    Throttle Position Sensor No.2 Voltage (VTA2)

    0.6 to 1.1 V

    2.1 to 3.1 V

    3.2 to 4.8 V

    (Not fail-safe)

    4.6 to 4.98 V

    (Not fail-safe)

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

Note

P012011

Throttle / Pedal Position Sensor / Switch "A" Circuit Short to Ground

The output voltage of VTA1 is less than 0.56 V 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

SAE Code: P0122

MONITOR DESCRIPTION

The ECM uses the throttle position sensor to monitor the throttle valve opening angle. If the VTA1 terminal voltage is less than the threshold, the ECM will illuminate the MIL and store this DTC.

MONITOR STRATEGY

Related DTCs

P0122: Throttle position sensor 1 range check (low voltage)

Required Sensors/Components (Main)

Throttle position sensor

Required Sensors/Components (Related)

-

Frequency of Operation

Continuous

Duration

2 seconds

MIL Operation

Immediate

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever the following DTCs are not stored

None

All of the following conditions are met

-

Battery voltage

8 V or higher

Engine switch

On (IG)

Starter

Off

TYPICAL MALFUNCTION THRESHOLDS

VTA1 voltage

Less than 0.56 V

CONFIRMATION DRIVING PATTERN

HINT:

  • After repair has been completed, clear the DTC and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.

    Click here

  • When clearing the permanent DTCs, refer to the "CLEAR PERMANENT DTC" procedure.

    Click here

  1. Connect the Techstream to the DLC3.
  2. Turn the engine switch on (IG).
  3. Turn the Techstream on.
  4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
  5. Turn the engine switch off and wait for at least 30 seconds.
  6. Turn the engine switch on (IG) [A].
  7. Turn the Techstream on.
  8. Start the engine.
  9. With the vehicle stationary, fully depress and release the accelerator pedal [B].
  10. Idle the engine for 2 seconds or more [C].
  11. Enter the following menus: Powertrain / Engine / Trouble Codes [D].
  12. 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.
  13. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
  14. Input the DTC: P012011.
  15. 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

    HINT:

    • If the judgment result is NORMAL, the system is normal.
    • If the judgment result is ABNORMAL, the system is malfunctioning.
    • If the judgment result is INCOMPLETE, perform steps [B] through [D] again.
    • [A] to [D]: Normal judgment procedure.

      The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.

    • When clearing the permanent DTCs, do not disconnect the cable from the battery terminal or attempt to clear the DTCs during this procedure, as doing so will clear the universal trip and normal judgment histories.

FAIL-SAFE

When this DTC is 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 valve 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 angle, to allow the vehicle to continue running 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 turned off.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

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.

PROCEDURE

1.

READ VALUE USING TECHSTREAM (THROTTLE POSITION SENSOR NO.1 VOLTAGE)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Data List / Throttle Position Sensor No.1 Voltage.

Powertrain > Engine > Data List

Tester Display

Throttle Position Sensor No.1 Voltage

(e) Read the values displayed on the Techstream.

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

(g) Compare the value of the Data List item Throttle Position Sensor No.1 Voltage after disconnecting the throttle body with motor assembly connector to the value when the connector was connected.

Result

Proceed to

Changes from less than 0.56 V to higher than 4.535 V

A

Does not change from less than 0.56 V

B

HINT:

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

Click here

A

REPLACE THROTTLE BODY WITH MOTOR ASSEMBLY

B

2.

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

C16-5 (VC) - C32-121 (VCTA)

Always

Below 1 Ω

C16-6 (VTA) or C32-122 (VTA1) - Body ground

Always

10 kΩ or higher
OK

REPLACE ECM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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