Throttle position sensor (TP) is a potentiometer connected to the shaft
throttle valve on the throttle body. The throttle position sensor circuit consists of a 5 volt supply circuit and a ground circuit, both circuits controlled by the engine control unit (ECM). The ECM calculates the throttle position by monitoring the voltage on this signal circuit. As the accelerator pedal is moved, the output voltage of the throttle position sensor changes, thus changing the throttle opening angle. When the throttle is closed, the throttle position sensor output is low, about 0.5 volts. As the throttle valve opens, the output increases so that at wide open throttle, the output voltage will be 5 volts.
ECM calculates fuel delivery based on throttle opening angle (determined by the driver). A bad or worn throttle position sensor can cause an occasional injector slosh and rough idle because the ECM senses that the throttle is currently changing its position. A malfunction in any of the throttle position sensor circuits should cause a DTC to be set (DTC) P0121 or P0122. If one of the DTCs is set, the ECM will override the throttle position sensor default and the vehicle performance will be compensated to some extent.
DTC P0121 is the cause of high idle.
Withdrawal
1. Disable «-» battery wire.
2. Remove the throttle position sensor connector.
3. Remove the throttle position sensor mounting bolts and throttle.
Installation
1. With the throttle valve closed, install the TP sensor on the throttle shaft. Align the TP sensor with the bolt holes.
2. Tighten the throttle position sensor mounting screws to 2 Nm.
3. Connect the TP sensor connector.
4. Connect «-» battery wire.
