Throttle Position Sensor

The Throttle Position (TP) sensor is mounted on the throttle body assembly. The sensor is comprised of two potentiometers with common supply and ground circuits, and independent signal circuits. As the throttle opens, the signal wire on sensor 1 reads a higher voltage, and the voltage on signal wire for sensor 2 decreases. This is used as a feedback device to allow the ECM to compare the throttle body's present location to where it is commanded to be.

The ECM calculates the fuel delivery based on the throttle angle. A broken or loose TP sensor may cause intermittent bursts of fuel from an injector. This may cause an unstable idle because the ECM detects the throttle is moving.

Idle control is achieved by holding the throttle butterfly open a certain amount. There is not a separate idle air control bypass around the throttle body.

When installing new throttle body or ECM, the throttle position has to be learned by the ECM. To do this, turn Ignition On, Engine Off, for 30 seconds.

The following conditions have to be met:
^ Accelerator pedal at resting position.
^ Battery voltage is greater than 8 volts.
^ Vehicle speed equals zero.
^ ECT between 5.25°C (41°F) and 100°C (212°F).
^ IAT greater than 5.25°C (41 °F).
^ No throttle motor DTCs present.