Throttle Position Sensor: Description and Operation

Throttle Position Sensor

Description
To enable closed loop control, the position of the throttle plate is supplied to the ECM by two feedback potentiometers in the throttle body. The feedback potentiometers have a common 5 V supply and a common ground connection from the ECM, and produce separate linear signal voltages to the ECM proportional to the position of the throttle plate.

The ECM uses the signal from feedback potentiometer 1 as the primary signal of throttle plate position, and the signal from feedback potentiometer 2 for plausibility checks.
^ The signal from feedback potentiometer 1 varies between 0.5 V (0% throttle open) and 4.5 V (100% throttle open).
^ The signal from feedback potentiometer 2 varies between 4.5 V (0% throttle open) and 0.5 V (100% throttle open)

There are two diagnostic checks on the output signal of this sensor: -
1. A range check, where a fault is detected if the signal voltage exceeds a minimum or maximum threshold.
2. A rationality check as detailed by the MAF sensor section.