Circuit Description

The DTC P0123 Throttle Position (TP) Sensor 1 Circuit High Voltage diagnostic detects an out of range sensor signal. The TP sensor 1 output provides the powertrain control module (PCM) with a signal voltage that is proportional to the throttle plate movement. The TP sensor used with the throttle actuator control (TAC) system is actually a Hall Effect switch. The Hall Effect switch is surrounded by a magnetic yoke that induces a flux in the magnetic field when the throttle shaft is rotated. The PCM provides a 5-volt reference voltage to the sensor circuits in the TAC module. An integrated circuit (IC) receives and converts the magnetic pulses into 2 separate TP signal, each with their own characteristics. Both TP sensor signal voltages are low at closed throttle and increase as the throttle opens. TP sensor 1 determines the actual throttle valve position. TP sensor 2 has a voltage that is more than twice that of TP sensor 1 at idle. TP sensor 2 provides a backup value for TP sensor 1.