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

Lexus ES (XZ10) Service Manual / Engine & Hybrid System / A25a-fxs (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.

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.

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)

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
Both of the following conditions are met	-
Auxiliary battery voltage	8 V or higher
Power switch	On (IG)

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

Connect the Techstream to the DLC3.
Turn the power switch on (IG).
Turn the Techstream on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the power switch off and wait for at least 30 seconds.
Turn the power switch on (IG) [A].
Turn the Techstream on.
Put the engine in Inspection Mode (Maintenance Mode).
Click here
Start the engine.
With the vehicle stationary, fully depress and release the accelerator pedal [B].
HINT:

During charge control, the engine speed is set at idle. Therefore, the engine speed will not increase when the accelerator pedal is depressed. In this case, perform step [B] after charge control has completed.
Idle the engine for 2 seconds or more [C].
Enter the following menus: Powertrain / Engine / Trouble Codes [D].
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.
Enter the following menus: Powertrain / Engine / Utility / All Readiness.
Input the DTC: P012011.

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 auxiliary 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 7.5° 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 engine torque request signal sent from the hybrid vehicle control ECU, to allow the vehicle to continue being driven 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 power switch is turned off.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Vehicle Control History may be stored in the hybrid vehicle control ECU assembly if the engine is malfunctioning. Certain vehicle condition information is recorded when Vehicle Control History is stored. Reading the vehicle conditions recorded in both the Freeze Frame Data and Vehicle Control History can be useful for troubleshooting.
Click here

(Select Powertrain in Health Check and then check the time stamp data.)

Click here
If any "Engine Malfunction" Vehicle Control History item has been stored in the hybrid vehicle control ECU assembly, make sure to clear it. However, as all Vehicle Control History items are cleared simultaneously, if any Vehicle Control History items other than "Engine Malfunction" are stored, make sure to perform any troubleshooting for them before clearing Vehicle Control History.
Click here

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 power switch on (IG).

(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

REPLACE THROTTLE BODY WITH MOTOR ASSEMBLY

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

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

(b) Disconnect the ECM connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
C57-2 (VC) - C88-109 (VCTA)	Always	Below 1 Ω
C57-1 (VTA) or C88-108 (VTA1) - Body ground	Always	10 kΩ or higher

REPLACE ECM

REPAIR OR REPLACE HARNESS OR CONNECTOR

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