2001 TOYOTA HIGHLANDER o2 sensor

- DIAGNOSTICSSFI SYSTEM (2AZ-FE)
05-257
447 Author
: Date
:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
DTC P2120 THROTTLE/PEDAL POSITION
SENSOR/SWITCH ºDº CIRCUIT
DTC P2122 THROTTLE/PEDAL POSITION
SENSOR/SWITCH ºDº CIRCUIT LOW INPUT
DTC P2123 THROTTLE/PEDAL POSITION
SENSOR/SWITCH ºDº CIRCUIT HIGH INPUT
DTC P2125 THROTTLE/PEDAL POSITION
SENSOR/SWITCH ºEº CIRCUIT
DTC P2127 THROTTLE/PEDAL POSITION
SENSOR/SWITCH ºEº CIRCUIT LOW INPUT
DTC P2128 THROTTLE/PEDAL POSITION
SENSOR/SWITCH ºEº CIRCUIT HIGH INPUT
DTC P2138 THROTTLE/PEDAL POSITION
SENSOR/SWITCH ºDº/ºEº VOLTAGE
CORRELATION
HINT:
This is the repair procedure for the ºaccelerator pedal position sensorº.
05ITG-02

A19694A19694A19803
Accelerator Pedal
Position Sensor
ECM Magnet
Magnet
IC No. 2 IC No. 1
EPA2
VCP2 VPA2 EPA
VCPA VPA
Accelerator Pedal Position Sensor Output Voltage (V)Usable Range
Accelerator Pedal Turning Angle (deg)*
1*2
Accelerator Pedal Released
Accelerator Pedal Fully Depressed 0.8 3.4 to 5.35
25 0
*1:
*
2:
2.6 to 4.5
1.6 05-258
- DIAGNOSTICSSFI SYSTEM (2AZ-FE)
448 Author
: Date
:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
CIRCUIT DESCRIPTION
HINT:

This Electronic Throttle Control System (ETCS) does not use a throttle cable.

This description is for the accelerator pedal position sensor.
The Accelerator Pedal Position (APP) sensor is mounted on the accelerator pedal to detect the angle of the
accelerator 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 monitors the accelerator pedal angle from VPA and VPA2 signal outputs, and controls the throttle
motor based on these signals.

- DIAGNOSTICSSFI SYSTEM (2AZ-FE)
05-259
449 Author
: Date
:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)DTC No.
DTC Detection Condition
(All of the following are 1 trip detection logic)Trouble Area
P2120Condition (a) continues for 0.5 sec. or more:
(a) VPA is 0.2 V or less or VPA is 4.8 V or more
Accelerator pedal position sensor

ECM
P2122VPA is 0.2 V or less for 0.5 sec. or more when VPA2 output
indicates accelerator pedal is opened

Accelerator pedal position sensor

Open in VCP1 circuit

VPA circuit open or ground short

ECM
P2123Condition (a) continues for 2.0 sec. or more:
(a) VPA is 4.8 V or more
Accelerator pedal position sensor

Open in EPA circuit

ECM
P2125Condition (a) continues for 0.5 sec. or more:
(a) (VPA2 is 0.5 V or less) or (VPA2 is 4.8 V or more)
Accelerator pedal position sensor

ECM
P2127VPA2 is 0.5 V or less for 0.5 sec. or more when VPA output
indicates accelerator pedal is opened

Accelerator pedal position sensor

Open in VCP2 circuit

VPA2 circuit open or ground short

ECM
P2128
Conditions (a) and (b) continue for 2.0 sec. or more:
(a) VPA2 is 4.8 V or more
(b) VPA is 0.2 V or more and VPA is 3.45 V or less
Accelerator pedal position sensor

Open in EPA2 circuit

ECM
P2138
Condition (a) or (b) continues for 2.0 sec. or more:
(a) Difference between VPA and VPA2 is 0.02 V or less
(b) VPA is 0.2 V or less and VPA2 is 0.5 V or less
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 hand-held tester
or the OBD II scan tool to confirm the accelerator pedal position sensor output voltage.
Accelerator pedal position expressed as voltage output
Trouble AreaAccelerator pedal releasedAccelerator pedal depressedTrouble Area
ACCEL POS #1ACCEL POS #2ACCEL POS #1ACCEL POS #2
VCP circuit open0 to 0.2 V0 to 0.2 V0 to 0.2 V0 to 0.2 V
VPA circuit open or ground short0 to 0.2 V1.2 to 2.0 V0 to 0.2 V3.4 to 5.3 V
VPA2 circuit open or ground short0.5 to 1.1 V0 to 0.2 V2.6 to 4.5 V0 to 0.2 V
EPA circuit open4.5 to 5.5 V4.5 to 5.5 V4.5 to 5.5 V4.5 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 the 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:
The voltage output of the VPA is below 0.2 V or exceeds 4.8 V.
FAIL-SAFE
The accelerator pedal position sensor has 2 (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 2 sensor circuits
and switches to fail-safe mode. In fail-safe mode, the remaining 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 to be fully closed.
In this case, the throttle valve will remain closed as if the engine is idling.
If a ºpassº 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.

05-260
- DIAGNOSTICSSFI SYSTEM (2AZ-FE)
450 Author
: Date
:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
MONITOR STRATEGY
Related DTCs
P2120: APP (Accelerator pedal position) Sensor 1 range check (chattering)
P2122: APP sensor 1 range check (low voltage)
P2123: APP sensor 1 range check (high voltage)
P2125: APP sensor 2 range check (chattering)
P2127: APP sensor 2 range check (low voltage)
P2128: APP sensor 2 range check (high voltage)
P2138: APP sensor range check (correlation)
Required sensors / components (Main)APP sensor
Required sensors / components (Related)-
Frequency of operationContinuous
Duration0.5 sec.: P2120, P2122, P2125 and P2127
2 sec.: P2123, P2128 and P2138
MIL operationImmediate
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
The monitor will run whenever these DTCs are not presentSee page 05-16
TYPICAL MALFUNCTION THRESHOLDS
P2120:
Either of the following conditions is met:Condition 1 or 2
1. VPA1 voltage when VPA2 is 0.97 or more0.2 V or less
2. VPA1 voltage4.8 V or more
P2122:
VPA1 voltage when VPA2 is 0.97 or more0.2 V or less
P2123:
VPA1 voltage4.8 V or more
P2125:
Either of the following conditions is met:Condition 1 or 2
1. VPA2 voltage when VPA1 is 0.97 or more0.5 V or less
2. VPA2 voltage when VPA1 is 0.2 to 3.45 V4.8 V or more
P2127:
VPA2 voltage when VPA1 is 0.97 or more0.5 V or less
P2128:
VPA2 voltage when VPA1 is 0.2 to 3.45 V4.8 V or more
P2138:
Either of the following conditions is met:Condition 1 or 2
1. Difference betrween VPA 1 and VPA2 voltage0.02 V or less
Condition 2-
VPA1 voltage0.2 V or less
VPA2 voltage0.5 V or less
COMPONENT OPERATING RANGE
VPA voltage0.5 to 4.5 V
VPA2 voltage1.2 to 4.8 V

A80021
A27
Accelerator Pedal
Position Sensor
EPA
EPA2
VCP2VPA2VPA
5
2
1 3 46
VCPAE5
E5
E5 E5 E5 E5
28
29
27 23 26 22ECM
EPA
EPA2
VCP2 VPA2VCPAVPA
BR
L G
W B
R
FI7052DepressedReleased
- DIAGNOSTICSSFI SYSTEM (2AZ-FE)
05-261
451 Author
: Date
:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the
engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help deter-
mine 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.
Hand-held tester:
1 READ VALUE OF HAND-HELD TESTER (ACCEL POS #1 AND ACCEL POS #2)
(a) Connect the hand-held tester to the DLC3.
(b) Turn the ignition switch ON.
(c) On the hand-held tester, enter the following menus:
DIAGNOSIS / ENHANCED OBD II / DATA LIST / ETCS
/ ACCEL POS #1 and ACCEL POS #2º and read its value
displayed on the hand-held tester.
Standard:
Accelerator PedalACCEL POS #1ACCEL POS #2
Released0.5 to 1.1 V1.2 to 2.0 V
Depressed2.6 to 4.5 V3.4 to 5.3 V
OK Go to step 5
NG

B53781
A67445A92629
A27
Accelerator Pedal
Position Sensor
VPA
EPA
VCPA
VPA2 EPA2 VCP2 Wire Harness Side
E5
ECM VPA
EPAVCPA
VPA2
EPA2VCP2
A19521
A53765A92544
A27
Accelerator Pedal
Position Sensor
EPA (-)
VCPA (+)E5
ECM
VCP2 (+) EPA2 (-)
05-262
- DIAGNOSTICSSFI SYSTEM (2AZ-FE)
452 Author
: Date
:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
2 CHECK WIRE HARNESS (ACCELERATOR PEDAL POSITION SENSOR - ECM)
(a) Disconnect the A27 sensor connector.
(b) Disconnect the E5 ECM connector.
(c) Measure the resistance of the wire harness side connec-
tors.
Standard:
Tester ConnectionSpecified Condition
VPA (A27-6) - VPA (E5-22)
EPA (A27-5) - EPA (E5-28)
VCPA (A27-4) - VCPA (E5-26)
VPA2 (A27-3) - VPA2 (E5-23)
EPA2 (A27-2) - EPA2 (E5-29)
VCP2 (A27-1) - VCP2 (E5-27)
Below 1 W
VPA (A27-6) or VPA (E5-22) - Body ground
EPA (A27-5) or EPA (E5-28) - Body ground
VCPA (A27-4) or VCPA (E5-26) - Body ground
VPA2 (A27-3) or VPA2 (E5-23) - Body ground
EPA2 (A27-2) or EPA2 (E5-29) - Body ground
VCP2 (A27-1) or VCP2 (E5-27) - Body ground
10 kW or higher
NG REPAIR OR REPLACE HARNESS AND
CONNECTOR
OK
3 INSPECT ECM (VCPA AND VCP2 VOLTAGE)
(a) Disconnect the A27 sensor connector.
(b) Turn the ignition switch ON.
(c) Measure the voltage of the ECM connector.
Standard:
Tester ConnectionSpecified Condition
VCPA (E5-26) - EPA (E5-28)
VCP2 (E5-27) - EPA2 (E5-29)4.5 to 5.5 V
NG REPLACE ECM (See page 10-9)
OK

B53781
A67445A92629
A27
Accelerator Pedal
Position Sensor
VPA
EPA
VCPA
VPA2 EPA2 VCP2 Wire Harness Side
E5
ECM VPA
EPAVCPA
VPA2
EPA2VCP2
- DIAGNOSTICSSFI SYSTEM (2AZ-FE)
05-263
453 Author
: Date
:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
4 REPLACE ACCELERATOR PEDAL ROD ASSY (See page 10-1 1)
GO
5 READ OUTPUT DTC (ACCELERATOR PEDAL POSITION SENSOR DTCS ARE
OUTPUT AGAIN)
(a) Clear the DTC (see page 05-38).
(b) Start the engine.
(c) Run the engine at idle for 15 seconds or more.
(d) Read the DTC.
Result:
Display (DTC Output)Proceed to
P2120, P2122, P2123, P2125, P2127, P2128 and/or P2138 are output againA
No DTC outputB
B SYSTEM OK
A
REPLACE ECM (See page 10-9)
OBD II scan tool (excluding hand-held tester):
1 CHECK WIRE HARNESS (ACCELERATOR PEDAL POSITION SENSOR - ECM)
(a) Disconnect the A27 sensor connector.
(b) Disconnect the E5 ECM connector.
(c) Measure the resistance of the wire harness side connec-
tors.
Standard:
Tester ConnectionSpecified Condition
VPA (A27-6) - VPA (E5-22)
EPA (A27-5) - EPA (E5-28)
VCPA (A27-4) - VCPA (E5-26)
VPA2 (A27-3) - VPA2 (E5-23)
EPA2 (A27-2) - EPA2 (E5-29)
VCP2 (A27-1) - VCP2 (E5-27)
Below 1 W
VPA (A27-6) or VPA (E5-22) - Body ground
EPA (A27-5) or EPA (E5-28) - Body ground
VCPA (A27-4) or VCPA (E5-26) - Body ground
VPA2 (A27-3) or VPA2 (E5-23) - Body ground
EPA2 (A27-2) or EPA2 (E5-29) - Body ground
VCP2 (A27-1) or VCP2 (E5-27) - Body ground
10 kW or higher
NG REPAIR OR REPLACE HARNESS AND
CONNECTOR
OK

A19521
A53765A92544
A27
Accelerator Pedal
Position Sensor
EPA (-)
VCPA (+)E5
ECM
VCP2 (+) EPA2 (-)
05-264
- DIAGNOSTICSSFI SYSTEM (2AZ-FE)
454 Author
: Date
:
2005 HIGHLANDER REPAIR MANUAL (RM1144U)
2 INSPECT ECM (VCPA AND VCP2 VOLTAGE)
(a) Disconnect the A27 sensor connector.
(b) Turn the ignition switch ON.
(c) Measure the voltage of the ECM connector.
Standard:
Tester ConnectionSpecified Condition
VCPA (E5-26) - EPA (E5-28)
VCP2 (E5-27) - EPA2 (E5-29)4.5 to 5.5 V
NG REPLACE ECM (See page 10-9)
OK
3 REPLACE ACCELERATOR PEDAL ROD ASSY (See page 10-1 1)
GO
4 READ OUTPUT DTC (ACCELERATOR PEDAL POSITION SENSOR DTCS ARE
OUTPUT AGAIN)
(a) Clear the DTC (see page 05-38).
(b) Start the engine.
(c) Run the engine at idle for 15 seconds or more.
(d) Read the DTC.
Result:
Display (DTC Output)Proceed to
P2120, P2122, P2123, P2125, P2127, P2128 and/or P2138 are output againA
No DTC outputB
B SYSTEM OK
A
REPLACE ECM (See page 10-9)