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Home >> Toyota >> 2004 >> ECHO 2D Sedan, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Diagnostics >> DTC Tests >> DTC P0120: Throttle/Pedal Position Sensor/Switch "A" Circuit, DTC P0122: Throttle/Pedal Position Sensor/Switch "A" Circuit Low Input, DTC P0123: Throttle/Pedal Position Sensor/Switch "A" Circuit High Input >> Circuit Description
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Circuit Description

Fig 1: Identifying Throttle/Pedal Position Sensor/Switch Circuit Description
G02905083Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

The throttle position sensor is mounted in the throttle body and detects the throttle valve opening angle.

When the throttle valve is fully closed, a voltage of approximately 0.3 to 0.8 V is applied to terminal VTA of the ECM. The voltage applied to terminal VTA of the ECM increases in proportion to the opening angle of the throttle valve and becomes approximately 3.2 to 4.9 V when the throttle valve is fully opened. The ECM judges the vehicle driving conditions from these signals input from terminal VTA, uses them as one of the conditions for the air-fuel ratio correction, power increase correction and fuel-cut control etc.

Fig 2: DTC Detection Condition Table
G02905084Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

After confirming DTCs, use the hand-held tester or the OBD II scan tool to confirm the throttle valve opening percentage and closed throttle position switch condition.

Fig 3: Throttle Valve Opening Position Expressed As Percentage Table
G02905085Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002