Circuit Description

The throttle position (TP) sensors 1 and 2 are located within the throttle body assembly. Each sensor has the following circuits:

• A 5-volt reference circuit
• A low reference circuit
• A signal circuit

This provides the engine control module (ECM) with a signal voltage proportional to the throttle plate movement. The TP sensor 1 signal voltage at closed throttle is near the 5-volt reference circuit and decreases as the throttle plate is opened. The TP sensor 2 signal voltage at closed throttle is near the low reference circuit and increases as the throttle plate is opened. If the ECM detects that the TP sensor 1 signal voltage is more than the predicted range, DTC P0123 sets.