Throttle Position Sensor

PRINCIPLE OF OPERATION, THROTTLE POSITION SENSOR






Throttle Position Sensor--consists of a potentiometer connected to the shalt of the throttle butterfly.

The control module supplies the sensor with 5 V from pin 42 and grounds it via pin 67. The voltage from the sensor goes to pin 45 of the control module and is proportional to the throttle opening.


At idling speed the voltage is about 0.5 V and at wide open throttle about 4.5 V. The control module uses the voltage from the sensor to identify idling, partially open throttle and wide open throttle. When idling is identified, the control module uses a special ignition control matrix to adjust idling speed.

Oxygen (Lambda) control is disconnected at wide open throttle.

Fuel injection is switched off if the starter motor cranks the engine while the throttle is wide open.

A richer mixture is produced during acceleration and a leaner mixture during deceleration or engine overrun. The maximum boost pressure also depends on the position of the throttle. If the sensor is unserviceable or if there is no continuity in the circuit, the control module will use wide open throttle as a default and the CHECK ENGINE malfunction indicator lamp (MIL) in the main instrument display will light up.

Cars with Electronic Throttle System (ETS)--The throttle position sensor is built into the throttle body and forms part of the electronic throttle system.

The ETS sends a throttle position signal to pin 57 of the Trionic control module. This is a 200 Hz PWM signal which always has a pulse ratio of 5% at idling speed (about 0.7 V) and of about 90% at wide open throttle (about 12 V).