P0121-P0123

THROTTLE POSITION SENSOR

Fig. 1 TP Sensor:

Monitoring Procedure
The sensor output is monitored under steady driving conditions. The output is compared to the expected value (which is mapped against engine load and RPM). If the difference between these values is above a threshold then the range / performance failure judgement is made. The diagnostic trouble code (DTC) is stored if the failure judgement is made on two successive trips.

Throttle position is detected by the Throttle Position Sensor (TPS) which reports to the engine control module (ECM). The closed throttle position switch (idle switch) is integral to the throttle position sensor.

Structure of TPS
The throttle position sensor is a potentiometer. It is installed on the throttle cable bracket which is connected to the throttle body. As throttle position changes, the TP Sensor sends a voltage signal to the ECM.