P2121

4GR-FSE ENGINE CONTROL: SFI SYSTEM: P2121: Throttle / Pedal Position Sensor / Switch "D" Circuit Range / Performance
P2121 - Throttle / Pedal Position Sensor / Switch "D" Circuit Range / Performance

DESCRIPTION

HINT
- These DTCs relate to the accelerator pedal sensor assembly.
- This electronic throttle control system does not use a throttle cable.
The accelerator pedal sensor assembly is mounted on the accelerator pedal bracket and has 2 sensor circuits: VPA (main) and VPA2 (sub). This sensor is a non-contact type. It uses Hall-effect elements in order to yield accurate signals, even in extreme conditions. The voltage, which is applied to terminals VPA and VPA2 of the ECM, varies between 0 V and 5 V in proportion to the operating angle of the accelerator pedal (throttle valve). A signal from VPA indicates the actual accelerator pedal operating 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 accelerator pedal sensor assembly itself.

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









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 voltage outputs 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 sets a DTC.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





CONFIRMATION DRIVING PATTERN





- Connect the Techstream to the DLC3.

- Turn the engine switch on (IG) and turn the Techstream on.

- Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) DTC Check / Clear.

- Turn the engine switch off.

- Turn the engine switch on (IG) and turn the Techstream on [A].

- Fully depress and release the accelerator pedal [B].

- Check that 20 seconds or more have elapsed since the DTCs were cleared.

- Enter the following menus: Powertrain / Engine / Utility / All Readiness.

- Input the DTC: P2121.

- Check the DTC judgment result [C].





HINT
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows INCOMPLETE or UNKNOWN, perform steps [B] and [C] again.
- If the test result is UNKNOWN, enter the following menus: Powertrain / Engine / Trouble Codes / Pending.

- Read Pending DTCs.

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

- If the test result is INCOMPLETE or UNKNOWN and no pending DTC is output, perform a universal trip and check for permanent DTCs DTC Check / Clear.

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 sensor assembly 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 limp mode. In limp mode, the functioning circuit is used to calculate the accelerator pedal angle to allow the vehicle to continue driving. If both circuits malfunction, the ECM regards the 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 engine switch is turned off, the fail-safe operation stops and the system returns to a normal condition.

WIRING DIAGRAM





INSPECTION PROCEDURE

HINT
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.

PROCEDURE

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

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

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

(e) Read the DTCs.

Result:





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

B -- GO TO DTC CHART SFI System
A -- Continue to next step.

2. READ VALUE USING TECHSTREAM (ACCEL SENSOR OUT NO. 1 AND ACCEL SENSOR OUT NO. 2)

(a) Connect the Techstream to the DLC3.





(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

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

(e) Read the values displayed on the Techstream.

Standard Voltage:





NG -- REPLACE ACCELERATOR PEDAL SENSOR ASSEMBLY

OK -- CHECK FOR INTERMITTENT PROBLEMS

3. REPLACE ACCELERATOR PEDAL SENSOR ASSEMBLY

(a) Replace the accelerator pedal sensor assembly Removal.

NEXT -- Continue to next step.

4. CHECK WHETHER DTC OUTPUT RECURS (DTC P2121)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Clear the DTCs DTC Check / Clear.

(e) Start the engine and warm it up.

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

(g) Enter the following menus: Powertrain / Engine / Trouble Codes.

(h) Read the DTCs.

Result:





B -- REPLACE ECM Removal

A -- END