2UZ-FE ENGINE CONTROL: SFI SYSTEM: DESCRIPTION (2008 Sequoia)

Last Modified: 11-29-2007		1.6 C
Service Category: Engine/Hybrid System	Section: Engine Control
Model Year: 2008	Model: Sequoia	Doc ID: RM000000PFZ06OX
Title: 2UZ-FE ENGINE CONTROL: SFI SYSTEM: DESCRIPTION (2008 Sequoia)

DTC

P2121

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

DESCRIPTION

HINT:

Refer to DTC P2120 .

DTC No.	DTC Detection Condition	Trouble Area
P2121	Difference between VPA and VPA2 less than 0.4 V, or more than 1.2 V for 0.5 seconds (1 trip detection logic)	Accelerator Pedal Position (APP) sensor ECM

MONITOR DESCRIPTION

When the difference between the output voltages of VPA and VPA2 deviates from the standard, the ECM determines that the Accelerator Pedal Position (APP) sensor is malfunctioning. The ECM turns on the MIL and the DTC is stored.

MONITOR STRATEGY

Related DTCs	P2121: APP sensor rationality
Required Sensors/Components (Main)	APP sensor
Required Sensors/Components (Related)	-
Frequency of Operation	Continuous
Duration	0.5 seconds
MIL Operation	Immediate
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever following DTCs not present	None
Either of following conditions 1 or 2 met:	-
1. Ignition switch	ON
2. Throttle actuator power	ON

TYPICAL MALFUNCTION THRESHOLDS

Difference between VPA voltage (learned value) and VPA2 voltage (learned value)

Less than 0.4 V, or more than 1.2 V

FAIL-SAFE

The APP sensor has two (main and sub) sensor circuits. If a malfunction occurs in either of the sensor circuits, the ECM detects the abnormal signal voltage difference between the two sensor circuits and switches to limp mode. In limp mode, the functioning circuit is used to calculate the accelerator pedal opening angle to allow the vehicle to continue driving. If both circuits malfunction, the ECM regards the opening angle of the accelerator pedal as being fully closed. In this case, the throttle valve remains closed as if the engine is idling.

If a pass condition is detected and then the ignition switch is turned off, the fail-safe operation stops and the system returns to a normal condition.

WIRING DIAGRAM

Refer to DTC P2120 .

INSPECTION PROCEDURE

HINT:

This DTC relates to the Accelerator Pedal Position (APP) sensor.
Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. 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 ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P2121)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(d) Enter the following menus: Powertrain / Engine / Trouble Codes.

(e) Read DTCs.

Result

Result	Proceed to
P2121 is output	A
P2121 and other DTCs are output	B

HINT:

If any DTCs other than P2121 are output, troubleshoot those DTCs first.

2.	READ VALUE USING TECHSTREAM (ACCELERATOR POSITION SENSOR)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(d) Enter the following menus: Powertrain / Engine / Data List / ETCS / Accelerator Position No. 1 and Accelerator Position No. 2.

(e) Read the values displayed on the Techstream.

Standard Voltage:

Accelerator Pedal Operation	Accelerator Position No. 1	Accelerator Position No. 2
Released	0.5 to 1.1 V	1.2 to 2.0 V
Depressed	2.6 to 4.5 V	3.4 to 4.7 V

3.	REPLACE ACCELERATOR PEDAL

(a) Replace the accelerator pedal assembly .

4.	CHECK WHETHER DTC OUTPUT RECURS (DTC P2121)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(d) Clear DTCs .

(e) Start the engine.

(f) Allow the engine to idle for 15 seconds.

(g) Enter the following menus: Powertrain / Engine / Trouble Codes.

(h) Read DTCs.

Result

Result	Proceed to
P2121 is output	A
No DTC is output	B