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
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
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