Toyota Sequoia (2005). Manual - part 144

A19694

A19803

5

3.7 to 4.4

2.9 to 3.6

1.6

1.4

0

25

IC No. 1

IC No. 2

Accelerator Pedal
Position Sensor

ECM

VPA

EPA

VCPA

VPA2

EPA2

VCP2

Usable Range

Magnet

Magnet

Accelerator Pedal Position Sensor Output V

oltage (V)

: Accelerator Pedal Fully Released

: Accelerator Pedal Fully Depressed

Accelerator Pedal Turning Angle (deg)

*

2

*

1

*

1

*

2

–

DIAGNOSTICS

ENGINE

DI–371

565

CIRCUIT DESCRIPTION

HINT:

This electrical throttle control system does not use a throttle cable.

This accelerator pedal position sensor is a non–contact type.

The accelerator pedal position sensor is mounted in the accelerator pedal to detect the angle of the accelera-
tor pedal. This sensor is electronically controlled and uses Hall–effect elements. 
In the accelerator pedal position sensor, the voltage applied to terminals VPA and VPA2 of the ECM changes
between 0 V and 5 V in proportion to the angle of the accelerator pedal. The VPA is a signal to indicate the
actual accelerator pedal angle and is used for the engine control. VPA2 is used to detect malfunctions of
the sensor itself.
The ECM judges the current angle of the accelerator pedal from these signals input from terminals VPA and
VPA2, and the ECM controls the throttle motor based on these signals.

DI–372

–

DIAGNOSTICS

ENGINE

566

DTC No.

DTC Detection Condition

(Open or short in accelerator pedal position sensor circuit)

Main trouble Area

P2120

Condition (a) continues for 0.5 seconds or more:

(a) VPA 

 0.2 V or VPA 



 4.8 V

Accelerator pedal position sensor

ECM

P2122

Condition (a) and (b) continues for 0.5 seconds or more:

(a) VPA 

 0.2 V

(b) VPA2 



 0.97 deg

Accelerator pedal position sensor

VCPA circuit open

VPA circuit open or ground short

ECM

P2123

Condition (a) continues for 2.0 seconds or more:

(a) VPA 



 4.8 V

Accelerator pedal position sensor

EPA circuit open

ECM

P2125

Condition (a) continues for 0.5 seconds or more:

(a) VPA2 

 0.5 V or VPA2 



 4.8 V and 0.2 V 

 VPA 

 3.45

V

Accelerator pedal position sensor

ECM

P2127

Condition (a) and (b) continues for 0.5 seconds or more:

(a) VPA2 

 0.5 V

(b) VPA 



 0.97 deg

Accelerator pedal position sensor

VCP2 circuit open

VPA2 circuit open or ground short

ECM

P2128

Condition (a) and (b) continues for 2.0 seconds or more:

(a) VPA2 



 4.8 V

(a) 0.2 V 

 VPA 

 3.45 V

Accelerator pedal position sensor

EPA circuit open

ECM

P2138

Condition (a) or (b) continues for 2.0 seconds or more:

(a) |VPA – VPA2| 

 0.02 V

(b) VPA 

 0.2 V and VPA2 

 0.5 V

VPA and VPA2 circuit are short circuited

Accelerator pedal position sensor

ECM

HINT:
After confirming DTC P2120, P2122, P2123, P2125, P2127, P2128 and P2138 use the OBD II scan tool
or the hand–held tester to confirm the accelerator pedal opening percentage.

Accelerator pedal position expressed as voltage

Trouble area

Accelerator pedal completely released

Accelerator pedal fully depressed

Trouble area

ACCEL POS #1

ACCEL POS #2

ACCEL POS #1

ACCEL POS #2

VC circuit open

0 to 0.2 V

0 to 0.2 V

0 to 0.2 V

0 to 0.2 V

VPA circuit open or ground short

0 to 0.2 V

1.2 to 2.0 V

0 to 0.2 V

3.4 to 5.3 V

VPA2 circuit open or ground short

0.5 to 1.1 V

0 to 0.2 V

2.6 to 4.5 V

0 to 0.2 V

E2 circuit open

4.5 to 5.5 V

4.5 to 5.5 V

4.5 to 5.5 V

4.5 to 5.5 V

MONITOR DESCRIPTION

When VPA or VPA2 deviates from the standard, or the difference between the voltage outputs of the two
sensors is less than threshold, the ECM concludes that there is a defect in the accelerator pedal position
sensor. The ECM turns on the MIL and a DTC is set.
Example: 
When the voltage output of the VPA is below 0.2 V or exceeds 4.8 V.

FAIL SAFE

The accelerator pedal position sensor has two (main and sub) sensor circuits. If a malfunction occurs in ei-
ther 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 remaining circuit is used to calculate the accelerator
pedal opening to allow the vehicle to continue driving.
If both circuits malfunction, the ECM regards the opening angle of the accelerator pedal to be fully closed.
In this case, the throttle valve will remain 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 will stop
and the system will return to normal condition.

–

DIAGNOSTICS

ENGINE

DI–373

567

MONITOR STRATEGY

P2120

Accelerator position sensor 1 (VPA) range check
(Fluttering)

P2122

Accelerator position sensor 1 (VPA) range check
(Low voltage)

P2123

Accelerator position sensor 1 (VPA) range check
(High voltage)

Related DTCs

P2125

Accelerator position sensor 2 (VPA2) range
check (Fluttering)

P2127

Accelerator position sensor 2 (VPA2) range
check (Low voltage)

P2128

Accelerator position sensor 2 (VPA2) range
check (High voltage)

P2138

Accelerator position sensor correlation range
check

Required sensors/components

Accelerator position sensor

Frequency of operation

Continuous

Duration

2 sec.

MIL operation

Immediate

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

It

Specification

Item

Minimum

Maximum

The monitor will run whenever these

DTCs are not present

See page 

DI–18

Ignition switch

ON

Throttle control motor power

ON

DI–374

–

DIAGNOSTICS

ENGINE

568

TYPICAL MALFUNCTION THRESHOLDS

Detection Criteria

Threshold

P2120:

Either of the following conditions is met

Condition 1 or 2

1. VPA1 voltage when VPA2 is 0.97

°

 or more

0.2 V or less

2. VPA1 voltage

4.8 V or more

P2122:

VPA1 voltage when VPA2 is 0.97

°

 or more

0.2 V or less

P2123:

VPA1 voltage

4.8 V or more

P2125:

Either of the following conditions is met

Condition 1 or 2

1. VPA2 voltage when VPA1 is 0.97

°

 or more

0.5 V or less

2. VPA2 voltage when VPA1 is 0.2 to 3.45 V

4.8 V or more

P2127:

VPA2 voltage when VPA1 is 0.97

°

 or more

0.5 V or less

P2128:

VPA2 voltage when VPA1 is 0.2 to 3.45 V

4.8 V or more

P2138:

Either of the following condition is met:

Condition 1 or 2

1. Difference between VPA1 and VPA2 voltage

0.02 V or less

2. Both of the following conditions are met:

(a) and (b)

(a) VPA1 voltage

0.2 V or less

(b) VPA2 voltage

0.5 V or less

COMPONENT OPERATING RANGE

Parameter

Standard Value

VPA voltage

More than 0.2 V and less than 4.8 V

VPA2 voltage

More than 0.5 V and Less than 4.8 V

Difference between VPA and VPA2 voltages

More than 0.02 V