Toyota Tundra Service Manual: Throttle / Pedal Position Sensor / Switch "D" Circuit Range / Performance (P2121)

Toyota Tundra Service Manual / Engine, Hybrid System / 1ur-fe Engine Control / Sfi System / Throttle / Pedal Position Sensor / Switch "D" Circuit Range / Performance (P2121)

DESCRIPTION

HINT:

Refer to DTC P2120 (See page ).

DTC No.

DTC Detection Condition

Trouble Area

P2121

Either conditions (1) or (2) met for 0.5 seconds (1 trip detection logic):

  • (1) Difference between VPA and VPA2 is less than 0.4 V, or more than 1.2 V. (learned value of accelerator off position)
  • (2) Difference between VPA and VPA2 is greater than or equal to the specified value.
  • Accelerator pedal sensor assembly
  • ECM

MONITOR DESCRIPTION

The accelerator pedal position sensor is mounted on the accelerator pedal bracket. The accelerator pedal position sensor has 2 sensor elements and 2 signal outputs: VPA and VPA2. VPA is used to detect the actual accelerator pedal angle (used for engine control) and VPA2 is used to detect malfunctions in VPA. When the difference between the output voltages of VPA and VPA2 deviates from the standard, the ECM determines that the accelerator pedal position sensor is malfunctioning. The ECM turns on the MIL and stores the DTC.

MONITOR STRATEGY

Related DTCs

P2121: Accelerator pedal position sensor rationality

Required Sensors/Components (Main)

Accelerator pedal sensor assembly

Required Sensors/Components (Related)

-

Frequency of Operation

Continuous

Duration

-: Case 1

0.5 seconds: Case 2

MIL Operation

Immediate

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

ALL (Case 1 and Case 2)

Monitor runs whenever following DTCs not stored

P2120, P2122, P2123, P2125, P2127, P2128, P2138 (Accelerator pedal position sensor)

Either of following conditions 1 or 2 met:

-

1. Ignition switch

ON

2. Throttle actuator power

ON

Case 2

VPA2 voltage

Less than 4.84 V

Either of following conditions met:

a or b

a) VPA voltage - Learned VPA accelerator off position voltage

0.04 V or more

b) VPA2 voltage - Learned VPA2 accelerator off position voltage

0.04 V or more

TYPICAL MALFUNCTION THRESHOLDS

Case 1

Difference between VPA voltage and VPA2 voltage (learned value of accelerator off position)

Less than 0.4 V, or more than 1.2 V

Case 2

(VPA voltage - Learned VPA accelerator off position voltage) - (VPA2 voltage - Learned VPA2 accelerator off position voltage)

More than 0.165 V (varies with accelerator position)

CONFIRMATION DRIVING PATTERN

  1. Connect the Techstream to the DLC3.
  2. Turn the ignition switch to ON and turn the Techstream ON.
  3. Clear DTCs (even if no DTCs are stored, perform the clear DTC operation).
  4. Turn the ignition switch off and wait for at least 30 seconds.
  5. Turn the ignition switch to ON and turn the Techstream on [A].
  6. Wait for 5 seconds after turning the ignition switch to ON.
  7. Operate the accelerator pedal in accordance with the following procedure [B].
    1. Enter the following menus: Powertrain / Engine and ECT / Data List / Accel Sens. No. 1 Volt %, and Accel Sens. No.2 Volt %.
    2. Slowly depress the accelerator pedal until Accel Sens. No.1 Volt % is approximately 30% and Accel Sens. No.2 Volt % is approximately 46%, and then slowly release the accelerator pedal.
  8. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [C].
  9. Read the pending DTCs.

    HINT:

    • If a pending DTC is output, the system is malfunctioning.
    • If a pending DTC is not output, perform the following procedure.
  10. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
  11. Input the DTC: P2121.
  12. Check the DTC judgment result.

    Tester Display

    Description

    NORMAL

    • DTC judgment completed
    • System normal

    ABNORMAL

    • DTC judgment completed
    • System abnormal

    INCOMPLETE

    • DTC judgment not completed
    • Perform driving pattern after confirming DTC enabling conditions

    N/A

    • Unable to perform DTC judgment
    • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    HINT:

    • If the judgment result shows ABNORMAL, the system has a malfunction.
    • If the judgment result shows INCOMPLETE or N/A, perform steps [B] through [C] again.
  13. If no pending DTC is output, perform a universal trip and check for permanent DTCs (See page ).

    HINT:

    • If a permanent DTC is output, the system is malfunctioning.
    • If no permanent DTC is output, the system is normal.

FAIL-SAFE

The accelerator pedal position sensor has 2 (main and sub) sensor circuits. The ECM detects the abnormal signal voltage difference between the 2 sensor circuits and switches to fail-safe mode.

If the either of the 2 sensor circuits malfunctions, the ECM limits the engine output. If both of the circuits malfunction, the ECM regards the accelerator pedal as being released. In this case, the throttle valve remains 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 stops and the system returns to normal.

WIRING DIAGRAM

Refer to DTC P2120 (See page ).

CAUTION / NOTICE / HINT

HINT:

  • This DTC relates to the Accelerator Pedal Position (APP) sensor.
  • Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, 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.

PROCEDURE

1.

CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P2121)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(e) Read DTCs.

Result

Result

Proceed to

P2121 is output

A

P2121 and other DTCs are output

B

HINT:

If any DTCs other than P2121 are output, troubleshoot those DTCs first.

B

GO TO DTC CHART

A

2.

READ VALUE USING TECHSTREAM (ACCELERATOR PEDAL POSITIONSENSOR)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Data List / Accel Sensor Out No. 1 and Accel Sensor Out No. 2.

(e) Read the values displayed on the Techstream.

Standard Voltage:

Accelerator Pedal Operation

Accel Sensor Out No. 1

Accel Sensor Out No. 2

Released

0.5 to 1.1 V

1.2 to 2.0 V

Depressed

2.6 to 4.5 V

3.4 to 4.7 V

OK

CHECK FOR INTERMITTENT PROBLEMS

NG

3.

REPLACE ACCELERATOR PEDAL SENSOR ASSEMBLY

(a) Replace the accelerator pedal sensor assembly (See page ).

NEXT

4.

CHECK WHETHER DTC OUTPUT RECURS (DTC P2121)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Clear DTCs (See page ).

(e) Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

(f) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(g) Read DTCs.

Result

Result

Proceed to

P2121 is output

A

No DTC is output

B

A

REPLACE ECM

B

END

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