Toyota Tundra. Manual — part 1236

a. Connect the Techstream to the DLC3.

b. Turn the ignition switch ON.

c. Turn the Techstream ON.

d. Clear DTCs (See DTC CHECK/CLEAR ).

e. Allow the engine to idle for 15 seconds.

f. Securely apply the parking brake and move the shift lever to the D position (Procedure "A").

g. While depressing the brake pedal securely, fully depress the accelerator pedal for 5 seconds

(Procedure "B").

h. Enter the following menus: Powertrain/Engine and ECT/Trouble Codes.

i. Read DTCs.

HINT:

The output voltage of the throttle position sensor can be, checked during procedure "B" using the
Techstream. Variations in the output voltage indicate that the throttle actuator is in operation. To
check the output voltage using the Techstream, enter the following menus: Powertrain/Engine and
ECT/ETCS/Throttle Position No.1.

OK: No DTC output.

NG : REPLACE THROTTLE BODY ASSEMBLY (See REMOVAL )

OK : CHECK FOR INTERMITTENT PROBLEMS

DTC P2120 THROTTLE/PEDAL POSITION SENSOR/SWITCH "D" CIRCUIT; DTC P2122
THROTTLE/PEDAL POSITION SENSOR/SWITCH "D" CIRCUIT LOW INPUT; DTC P2123
THROTTLE/PEDAL POSITION SENSOR/SWITCH "D" CIRCUIT HIGH INPUT; DTC P2125
THROTTLE/PEDAL POSITION SENSOR/SWITCH "E" CIRCUIT; DTC P2127 THROTTLE/PEDAL
POSITION SENSOR/SWITCH "E" CIRCUIT LOW INPUT; DTC P2128 THROTTLE/PEDAL
POSITION SENSOR/SWITCH "E" CIRCUIT HIGH INPUT; DTC P2138 THROTTLE/PEDAL
POSITION SENSOR/ SWITCH "D"/"E" VOLTAGE CORRELATION

DESCRIPTION

HINT:

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

The Accelerator Pedal Position (APP) sensor is mounted on the accelerator pedal bracket and has 2 sensor
circuits: VPA (main) and VPA2 (sub). This sensor is a non-contact type and uses Hall-effect elements in order

CAUTION: Exercise extreme care and take precautions at procedure "A"

and "B" below. Failure to do so may result in the vehicle
unexpectedly rolling away.

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (1GR-FE) - Tundra

to yield accurate signals even in extreme driving conditions, such as at high speeds as well as very low speeds.
The voltage, which is applied to terminals VPA and VPA2 of the ECM, varies between 0.5 V and 4.5 V in
proportion to the operating angle of the accelerator pedal (throttle valve). A signal from VPA indicates the
actual accelerator pedal opening angle (throttle valve opening angle) and is used for engine control. A signal
from VPA2 conveys the status of the VPA circuit and is used to check the APP sensor itself.

The ECM monitors the actual accelerator pedal opening angle (throttle valve opening angle) through the signals
from VPA and VPA2, and controls the throttle actuator according to these signals.

Fig. 195: Accelerator Pedal Turning Angle Graph

DTC TROUBLE DETECTION CONDITION CHART

DTC

No.

DTC Detection Condition

Trouble Area

P2120

VPA fluctuates rapidly beyond upper and lower malfunction
thresholds for 0.5 seconds or more (1 trip detection logic)



Accelerator Pedal
Position (APP) sensor



ECM

P2122

VPA 0.4 V or less for 0.5 seconds or more when accelerator
pedal fully released (1 trip detection logic)



APP sensor



Open in VCP1 circuit



Open or ground short in
VPA circuit



ECM

P2123

VPA 4.8 V or more for 2.0 seconds or more (1 trip detection



APP sensor



Open in EPA circuit

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (1GR-FE) - Tundra

HINT:

When any of these DTCs are set, check the APP sensor voltage by entering the following menus:
Powertrain/Engine and ECT/Data List/ETCS/Accelerator Position No.1 and Accelerator Position No.2.

DATA LIST

logic)



ECM

P2125

VPA2 fluctuates rapidly beyond upper and lower malfunction
thresholds for 0.5 seconds or more (1 trip detection logic)



APP sensor



ECM

P2127

VPA2 1.2 V or less for 0.5 seconds or more when accelerator
pedal fully released (1 trip detection logic)



APP sensor



Open in VCP2 circuit



Open or ground short in
VPA2 circuit



ECM

P2128

Conditions (a) and (b) continue for 2.0 seconds or more (1 trip
detection logic):

a. VPA2 4.8 V or more

b. VPA between 0.4 V and 3.45 V



APP sensor



Open in EPA2 circuit



ECM

P2138

Condition (a) or (b) continues for 2.0 seconds or more (1 trip
detection logic):

a. Difference between VPA and VPA2 0.02 V or less

b. VPA 0.4 V or less and VPA2 1.2 V or less



Short between VPA and
VPA2 circuits



APP sensor



ECM

Trouble Area

Accelerator Position

No.1 When

Accelerator Pedal

Released

Accelerator Position

No.2 When

Accelerator Pedal

Released

Accelerator Position

No.1 When

Accelerator Pedal

Depressed

Accelerator Position

No.2 When

Accelerator Pedal

Depressed

VCP circuit

open

0 to 0.2 V

0 to 0.2 V

0 to 0.2 V

0 to 0.2 V

Open or

ground short

in VPA circuit

0 to 0.2 V

1.2 to 2.0 V

0 to 0.2 V

3.4 to 5.0 V

Open or

ground short

in VPA2

circuit

0.5 to 1.1 V

0 to 0.2 V

2.6 to 4.5 V

0 to 0.2 V

EPA circuit

open

4.5 to 5.0 V

4.5 to 5.0 V

4.5 to 5.0 V

4.5 to 5.0 V

Normal

condition

0.5 to 1.1 V

1.2 to 2.0 V

2.6 to 4.5 V

3.4 to 5.0 V

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (1GR-FE) - Tundra

HINT:

Accelerator pedal positions are expressed as voltages.

MONITOR DESCRIPTION

When either output voltage of VPA or VPA2 deviates from the standard range, or the difference between the
output voltages of the 2 sensor circuits is less than the threshold, the ECM determines that there is a malfunction
in the APP sensor. The ECM then illuminates the MIL and sets a DTC.

Example:

When the output voltage of VPA drops below 0.4 V for more than 0.5 seconds when the accelerator pedal is
fully depressed, DTC P2122 is set.

If the malfunction is not repaired successfully, a DTC is set 2 seconds after the engine is next started.

MONITOR STRATEGY

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

P2120:

Related DTCs

P2120: APP sensor 1 range check (fluctuating)
P2122: APP sensor 1 range check (low voltage)
P2123: APP sensor 1 range check (high voltage)
P2125: APP sensor 2 range check (fluctuating)
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 Operation

Continuous

Duration

0.5 seconds: P2120, P2122, P2125 and P2127
2.0 seconds: P2123, P2128 and P2138

MIL Operation

Immediate

Sequence of Operation

None

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

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (1GR-FE) - Tundra