Toyota Sequoia (2005). Manual - part 146

–

DIAGNOSTICS

ENGINE

DI–379

573

5

Check whether DTC

 

output recurs (DTC P2120, P2122, P2123, P2125, P2127,

P2128 or P2138)

PREPARATION:
(a)

Connect the hand–held tester to the DLC3.

(b)

Disconnect the battery terminals or remove the EFI No. 1 fuse and ETCS fuse (Clear DTCs).

(c)

Start the engine.

(d)

Drive the engine at idle for 15 seconds or more.

(e)

On the hand–held tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC
INFO / PENDING CODES.

CHECK:
Read the DTC output.
RESULT:

Display (DTC Output)

Proceed To

P2120, P2122, P2123,P2125, P2127, P2128 or P2138

A

No output

B

B

System is OK.

A

Replace ECM (See page 

SF–80

).

DI–380

–

DIAGNOSTICS

ENGINE

574

DTC

P2121

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

HINT:
This is repair procedure for the ”accelerator pedal position sensor”.

CIRCUIT DESCRIPTION

Refer to DTC P2120 on page 

DI–370

.

DTC No.

DTC Detecting Condition

Trouble Area

P2121

Conditions (a) and (b) continue for 0.5 seconds:

(a) Difference between VPA and VPA2 exceeds the threshold

(b) IDL is OFF

Accelerator pedal position sensor circuit

Accelerator pedal position sensor

ECM

MONITOR DESCRIPTION

The accelerator pedal position sensor is mounted on the accelerator pedal bracket. The accelerator pedal
position sensor has 2 sensor elements/signal outputs: VPA1 and VPA2. VPA1 is used to detect the actual
accelerator pedal angle (used for engine control) and VPA2 is used to detect malfunctions in VPA1. When
the difference between the voltage outputs of VPA1 and VPA2 deviates from the standard, the ECM con-
cludes the accelerator pedal position sensor has a malfunction. The ECM turns on the MIL and a DTC is
set.

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.

MONITOR STRATEGY

Related DTCs

P2121

Accelerator position sensor (rationality)

Required sensors/components

Accelerator position sensor

Frequency of operation

Continuous

Duration

0.5 sec.

MIL operation

Immediate

Sequence of operation

None

DID8H–01

FI7052

Depressed

Released

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DIAGNOSTICS

ENGINE

DI–381

575

TYPICAL ENABLING CONDITIONS

It

Specification

Item

Minimum

Maximum

The monitor will run whenever this DTC is
not present

See page 

DI–18

Either of the following conditions is met

Condition 1 or 2

1. Ignition switch

ON

2. Throttle control motor power

ON

TYPICAL MALFUNCTION THRESHOLDS

Detection Criteria

Threshold

Difference between VPA1 voltage (learned value) and VPA2
voltage (learned value)

Less than 0.4 V, or more than 1.2 V

WIRING DIAGRAM

Refer to DTC P2120 on page 

DI–370

.

INSPECTION PROCEDURE

HINT:
Read freeze frame data using 

the hand−held tester

. Freeze frame data records the engine conditions when

a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was
running or stopped, if the engine was warmed up or not, if the air–fuel ratio was lean or rich, as well as other
data from the time when a malfunction occurred.

1

Connect hand–held tester, and read the voltage for accelerator pedal position
sensor data.

PREPARATION:
(a)

Connect the hand–held tester to the DLC3.

(b)

Turn the ignition switch ON and push the hand–held tes-
ter main switch ON.

(c)

Enter the following menu: DIAGNOSIS / ENHANCED
OBD II / DATA LIST / ETCS / ACCEL POS #1 and ACCEL
POS #2.

CHECK:
Read the voltage for the accelerator pedal position sensor data.
OK:

Standard:

Accelerator pedal

ACCEL POS #1

ACCEL POS #2

Released

0.5 to 1.1 V

1.2 to 2.0 V

Depressed

2.6 to 4.5 V

3.4 to 5.3 V

OK

Replace ECM (See page 

SF–80

).

NG

A21022

Wire Harness Side:

A37

Accelerator Pedal Position Sensor

VCP2

EPA2 VPA2 VCPA EPA

VPA

B17417

E4

VPA2

VCPA

VPA

EPA2

EPA

VCP2

DI–382

–

DIAGNOSTICS

ENGINE

576

2

Check for open and short in harness and connector between accelerator pedal
position sensor and ECM.

PREPARATION:
(a)

Disconnect the A37 accelerator pedal position sensor
connector.

(b)

Disconnect the E4 ECM connector.

CHECK:
Measure the resistance between the wire harness side connec-
tors.
OK:

Standard (Check for open):

Tester Connection

Specified Condition

VPA (A37–6) – VPA (E4–18)

Below 1 

Ω

EPA (A37–5) – EPA (E4–20)

Below 1 

Ω

VCPA (A37–4) – VCPA (E4–26)

Below 1 

Ω

VPA2 (A37–3) – VPA2 (E4–19)

Below 1 

Ω

EPA2 (A37–2) – EPA2 (E4–21)

Below 1 

Ω

VCP2 (A37–1) – VCP2 (E4–27)

Below 1 

Ω

Standard (Check for short):

Tester Connection

Specified Condition

VPA (A37–6) or VPA (E4–18) – 

Body ground

10 k

Ω

 or higher

EPA (A37–5) or EPA (E4–20) – 

Body ground

10 k

Ω

 or higher

VCPA (A37–4) or VCPA (E4–26) – 

Body ground

10 k

Ω

 or higher

VPA2 (A37–3) or VPA2 (E4–19) – 

Body ground

10 k

Ω

 or higher

EPA2 (A37–2) or EPA2 (E4–21) – 

Body ground

10 k

Ω

 or higher

VCP2 (A37–1) or VCP2 (E4–27) – 

Body ground

10 k

Ω

 or higher

NG

Repair or replace harness or connector.

OK

Replace accelerator pedal pedal assembly.