Circuit Description

WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.

The throttle position (TP) sensor incorporates 2 ratiometric TP sensors into one housing. TP sensor 1 and TP sensor 2 each have a 5-volt reference circuit supplied by the throttle actuator control (TAC) module. The TAC module supplies each TP sensor with a low reference circuit. Each TP sensor supplies the TAC module with a signal voltage that is proportional to the throttle blade position. Both of the TP signal voltages increase as the throttle blade is opened. The TP sensor 1 and the accelerator pedal position (APP) sensor 1 share a 5-volt reference circuit that is bussed within the TAC module. The TP sensor 2 and the APP sensor 2 share a 5-volt reference circuit that is also bussed within the TAC module. When this DTC sets, the Reduced Engine Power indicator will be displayed.

This DTC incorporates the following diagnostic tests:

The TP sensor 1 signal circuit voltage out of range
The throttle blade minimum position for the TP sensor 1 out of range
The 5-volt reference of the TP sensor 1 tests out of range

If the PCM detects one or more of the TP sensor 1 tests are out of range, DTC P0120 sets.