P2121

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

CIRCUIT DESCRIPTION

DTC Detecting Condition:

The accelerator pedal position sensor is mounted on the accelerator pedal bracket. It has the 2 sensors to detect the accelerator position and a malfunction of the accelerator position sensor.

In the accelerator pedal position sensor, the voltage applied to the pedal terminals VPA and VPA2 of the ECM changes between 0 V to 5 V, in proportion to the opening angle of the accelerator pedal. The VPA is a signal to indicate the actual accelerator pedal opening angle which is used for the engine control, and the VPA2 is a signal to indicate the information about the opening angle which is used for detecting a malfunction. The ECM judges the current opening angle of the accelerator pedal from these signals input from terminals VPA and VPA2 and, the ECM controls the throttle motor based on these signals.

If this DTCs is stored, the throttle valve is locked at a certain opening angle. Also, the whole electronically controlled throttle operation is cancelled until the system returns to normal and the ignition switch is turned OFF.

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Conditions:

Typical Malfunction Thresholds:

The accelerator pedal position sensor is mounted on the accelerator pedal bracket and consists of two sensors VPA and VPA2. The VPA is used to detect accelerator pedal position, and the VPA2 is used to monitor the VPA and detect faults in the sensor itself. When difference between voltage outputs, of the VPA or VPA2 deviates from the standard range, the ECM concludes that there is a defect in the accelerator pedal position sensor. The ECM turns on the MIL and a DTC is set.

INSPECTION PROCEDURE

HINT: Read freeze frame data using the hand-held tester or the OBD II scan tool. 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.

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Step 5:

Hand-held tester

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Step 3:

OBD II scan tool (excluding hand-held tester)