DTC    P2121    Throttle / Pedal Position Sensor / Switch "D" Circuit Range / Performance


DESCRIPTION

Refer to DTC P2120 (Click here).

DTC No.
DTC Detection Condition
Trouble Area
P2121
Either of following conditions 1 or 2 met for 0.5 seconds (1 trip detection logic):
  1. 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. 2. Difference between VPA and VPA2 is greater than or equal to the specified value.
  1. Accelerator pedal sensor assembly
  2. 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 present
None
Either of following conditions met:
1 or 2
1. Time after ignition switch OFF to ON
0.012 seconds or more
2. Throttle actuator power
ON
Accelerator pedal position sensor circuit fail (P2120, P2122, P2123, P2125, P2127, P2128, P2138)
Not detected

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)|
0.165 V or more (varies with accelerator position)

CONFIRMATION DRIVING PATTERN


A256657E01

  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 procedure).
  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%, then slowly release the accelerator pedal.
  8. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [C].
  9. Read pending DTCs.

    HINT:
    1. If a pending DTC is output, the system is malfunctioning.
    2. 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.

    Techstream Display
    		Description
    NORMAL
    1. DTC judgment completed
    2. System normal
    ABNORMAL
    1. DTC judgment completed
    2. System abnormal
    INCOMPLETE
    1. DTC judgment not completed
    2. Perform driving pattern after confirming DTC enabling conditions
    N/A
    1. Unable to perform DTC judgment
    2. Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    HINT:
    1. If the judgment result shows NORMAL, the system is normal.
    2. If the judgment result shows ABNORMAL, the system has a malfunction.
    3. 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 (Click here).

    HINT:
    1. If a permanent DTC is output, the system is malfunctioning.
    2. If no permanent DTC is output, the system is normal.

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 ECM limits the engine output. If both circuits malfunction, the ECM regards the opening angle of the accelerator pedal as being fully closed. 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 (Click here).

INSPECTION PROCEDURE

HINT:
  1. This DTC relates to the accelerator pedal position sensor.
  2. Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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.
1.CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P2121)

  1. Connect the Techstream to the DLC3.

  1. Turn the ignition switch to ON.

  1. Turn the Techstream on.

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

  1. Read DTCs.

    Result 
    Result
    		Proceed to
    DTC P2121 is output
    		A
    DTC 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 (Click here)
A


2.READ VALUE USING TECHSTREAM (ACCELERATOR PEDAL POSITION SENSOR)
A208621E02

  1. Connect the Techstream to the DLC3.

  1. Turn the ignition switch to ON.

  1. Turn the Techstream on.

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

  1. 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 4.75 V
    Text in Illustration 
    *a
    		Depressed
    *b
    		Released


NG
Go to step 3
OK

CHECK FOR INTERMITTENT PROBLEMS (Click here)  

3.REPLACE ACCELERATOR PEDAL SENSOR ASSEMBLY

  1. Replace the accelerator pedal sensor assembly (Click here).


NEXT


4.CHECK WHETHER DTC OUTPUT RECURS (DTC P2121)

  1. Connect the Techstream to the DLC3.

  1. Turn the ignition switch to ON.

  1. Turn the Techstream on.

  1. Clear the DTCs (Click here).

  1. Turn the ignition switch off and wait for at least 30 seconds.

  1. Turn the ignition switch to ON and turn the Techstream on.

  1. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

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

  1. Read DTCs.

    Result 
    Result
    		Proceed to
    DTC P2121 is output
    		A
    DTC is not output
    		B


B
END
A

REPLACE ECM (Click here)