Throttle Position (TP) Sensor

Throttle Position (TP) Sensor

The TP sensor is located on the throttle housing and secured with two Torx head screws. The sensor is directly attached to the throttle disk spindle and its movement is proportional to throttle movement.

The TP sensor is a rotary potentiometer. The ECM supplies the sensor with a 5 volt supply and an earth path. The sensor returns a signal proportional to throttle disk position. Closed throttle is detected by the TP sensor which prompts the ECM to initiate idle speed control via the IAC valve.

Throttle disk movement causes voltage across the potentiometer to vary. The ECM calculates the rate of change of the voltage signal in positive (acceleration) or negative (deceleration) directions. From this the ECM can determine the required engine speed, rate of acceleration or, rate of deceleration and apply acceleration enrichment, deceleration fuel metering or over-run fuel cut-off.

If the TP sensor fails, the ECM enters a default mode and, using a substitute value, assumes that the throttle disk is fully closed.

NOTE: The position of the throttle disk is preset during manufacture and the throttle position setting screw MUST NOT be adjusted unless directed by TestBook. The TP sensor is not adjustable and the ECM is designed to learn the throttle closed position and adapt to any changes which may occur throughout the life of the engine. If the relationship between the TP sensor and the throttle disc is changed for any reason (renewal of TP sensor etc.), the TestBook throttle initialisation procedure MUST be carried out.