2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0121; Throttle / Pedal Position Sensor / Switch "A" Circuit Range / Performance Problem; 2007 MY LX470 [08/2006

Last Modified: 7-3-2017	6.8:8.0.40	Doc ID: RM000000UIH00NX
Model Year Start: 2007	Model: LX470	Prod Date Range: [08/2006 - ]
Title: 2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0121; Throttle / Pedal Position Sensor / Switch "A" Circuit Range / Performance Problem; 2007 MY LX470 [08/2006 - ]

DTC

P0121

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

DESCRIPTION

Refer to DTC P0120 .

DTC No.

DTC Detection Condition

Trouble Area

P0121

Difference between VTA1 and VTA2 voltage less than 0.8 V, or more than 1.6 V for 2 seconds

(1 trip detection logic)

Throttle Position (TP) sensor (built into throttle body)

MONITOR DESCRIPTION

The ECM uses the throttle position sensor to monitor the throttle valve opening angle.

This sensor includes 2 signals: VTA1 and VTA2. VTA1 is used to detect the throttle opening angle and VTA2 is used to detect malfunctions in VTA1. There are several checks that the ECM performs to confirm proper operation of the throttle position sensor and VTA.

There is a specific voltage difference expected between VTA and VTA2 for each throttle opening angle.

If the voltage output difference of the VTA1 and VTA2 deviates from the normal operating range, the ECM interprets this as a malfunction of the throttle position sensor. The ECM will illuminate the MIL and set a DTC. This monitor runs for 2 seconds (the first 2 seconds of engine idle) after the engine is started (1 trip detection logic).

MONITOR STRATEGY

Related DTCs	P0121: Throttle Position (TP) sensor rationality
Required Sensors/Components (Main)	TP sensor
Required Sensors/Components (Related)	-
Frequency of Operation	Continuous
Duration	Within 2 seconds
MIL Operation	Immediate
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Either of following conditions A or B is met	-
A. Ignition switch	ON
B. Electric throttle motor power	ON
TP sensor malfunction (P0120, P0122, P0123, P0220, P0222, P0223, P2135)	Not detected

TYPICAL MALFUNCTION THRESHOLDS

Either of following conditions is met	-
"Difference of TP sensor voltage between VTA1 and VTA2 x 0.8"	Higher than 1.6 V
"Difference of TP sensor voltage between VTA1 and VTA2 x 0.8"	Lower than 0.8 V

FAIL-SAFE

When any of these DTCs, as well as other DTCs relating to Electronic Throttle Control System (ETCS) malfunctions, are set, the ECM enters fail-safe mode. During fail-safe mode, the ECM cuts the current to the throttle actuator off, 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 ignition switch is then turned OFF.

WIRING DIAGRAM

Refer to DTC P0120 .

INSPECTION PROCEDURE

HINT:

Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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.
This is the repair procedure of the throttle position sensor.

PROCEDURE

1.	READ OTHER DTC OUTPUT (IN ADDITION TO DTC P0121)

(a) Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM to the DLC3.

(b) Turn the ignition switch ON.

(d) Read the DTCs.

Display (DTC output)	Proceed to
P0121	A
P0121 and other DTCs	B

HINT:

If any other codes besides P0121 are output, perform the troubleshooting for those codes first.

GO TO RELEVANT DTC CHART

REPLACE THROTTLE BODY