P2121

1GR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P2121: Throttle / Pedal Position Sensor / Switch "D" Circuit Range / Performance

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

CAUTION / NOTICE / HINT

DESCRIPTION
HINT: This DTC relates to the Accelerator Pedal Position (APP) sensor.

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 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 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 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.





HINT: When any of these DTCs are set, check the APP sensor voltage by selecting the following menu items on a Techstream: Powertrain / Engine and ECT / Data List / ETCS / Accelerator Position No. 1 and Accelerator Position No. 2.





HINT: Accelerator pedal positions are expressed as voltages.






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 a malfunctioning. The ECM turns on the MIL and the DTC is set.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





FAIL-SAFE

The accelerator pedal position sensor has two (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 two sensor circuits and switches to fail-safe mode. In fail-safe mode, the functioning circuit is used to calculate the accelerator pedal opening angle to allow the vehicle to continue driving. 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 a normal condition.

WIRING DIAGRAM







INSPECTION PROCEDURE
HINT: Read freeze frame data using a Techstream. Freeze frame data record 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. READ VALUE USING TECHSTREAM (ACCEL POS #1 AND ACCEL POS #2)




(a) Connect a Techstream to the DLC3.
(b) Turn the ignition switch ON and turn the tester ON.
(c) Select the following menu items: Powertrain / Engine and ECT / Data List / ETCS / Accel Sens. No. 1 Volt % and Accel Sens. No. 2 Volt %.
(d) Read the values displayed on the tester.
Standard Voltage:






OK -- REPLACE ACCELERATOR PEDAL ROD ASSEMBLY
NG -- Continue to next step.
2. CHECK HARNESS AND CONNECTOR (ACCELERATOR PEDAL POSITION SENSOR - ECM) P2120
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
3. REPLACE ACCELERATOR PEDAL ROD ASSEMBLY
Replace the accelerator pedal rod assembly Removal.
NEXT -- Continue to next step.
4. CHECK WHETHER DTC OUTPUT RECURS (DTC P2121)
(a) Connect a Techstream to the DLC3.
(b) Turn the ignition switch ON and turn the tester ON.
(c) Clear DTCs DTC Check / Clear.
(d) Start the engine.
(e) Allow the engine to idle for 15 seconds.
(f) Select the following menu items: Powertrain / Engine and ECT / Trouble Codes.
(g) Read DTCs.
Result:






B -- END
A -- REPLACE ECM