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Home >> Scion >> 2005 >> xB Automatic >> Repair and Diagnosis (Single Page) >> Engine Performance >> SFI System >> DTC P0120, P0122, P0123: Throttle/Pedal Position Sensor/Switch "A" Circuit, Low Input & High Input >> Circuit Description
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Circuit Description

The TP sensor is mounted on the throttle body and detects the throttle valve opening angle.

When the throttle valve is fully closed, the sensor transmits a signal voltage of approximately 0.3 to 1.0 V to terminal VTA of the ECM. This signal voltage increases in proportion to the opening angle of the throttle valve, reaching approximately 3.2 to 4.9 when the throttle valve is fully open.

The ECM determines the vehicle driving conditions from these signals and uses this information in functions such as air-fuel ratio correction, power increase correction and fuel-cut control.

Fig 1: Throttle/Pedal Position Sensor/Switch "A" Circuit Description
G03095783Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 2: DTC Chart
G03095784Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

INSPECTING THROTTLE VALVE OPENING ANGLE

Throttle Valve Fully Closed Throttle Valve Fully Open Trouble Areas
0% 0% VC circuit open VTA circuit open or short
Approximately 100 % Approximately 100 % E2 circuit open