Throttle Position (TP) Sensor Circuit Description

Throttle Position (TP) Sensor Circuit Description

The Throttle Position (TP) sensor (2) is a potentiometer. The TP sensor is connected to the throttle shaft (3) on the throttle body. The PCM (1) calculates throttle position by monitoring the voltage on the signal line. The TP sensor signal changes as the throttle valve angle is changed (accelerator pedal moved). The TP sensor signal voltage is low at a closed throttle position. The TP sensor signal voltage increases as the throttle valve opens so that at Wide Open Throttle (WOT), the output voltage should be above 4.0 volts.

The PCM calculates fuel delivery based on throttle valve angle (driver demand). A broken or loose TP sensor may cause intermittent bursts of fuel from an injector. This may cause an unstable idle because the PCM detects the throttle is moving. The following DTCs set when the PCM detects a malfunction with the TP sensor circuits:
^ DTC P0121 TP Sensor Circuit Insufficient Activity.
^ DTC P0122 TP Sensor Circuit Low Voltage.
^ DTC P0123 TP Sensor Circuit High Voltage.
^ DTC P1121 TP Sensor CKT Intermittent High Voltage.
^ DTC P1122 TP Sensor CKT Intermittent Low Voltage.