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Home >> Toyota >> 2005 >> ECHO 2D Sedan, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine - Diagnostics >> Circuit Inspection >> DTC P0120, P0122, P0123: Throttle/Pedal Position Sensor/Switch "A" Circuit Low/High Input >> Circuit Description
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Circuit Description

Fig 1: Throttle Position Sensor Circuit Description
G02590523Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

The throttle position sensor is mounted on 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 the 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 open. The ECM judges the vehicle driving conditions from this signal input from terminal VTA, and uses this information in calculations such as air-fuel ratio correction, power increase correction and fuel-cut control etc.

Fig 2: DTC Detecting Condition Table
G02590524Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NOTE: After confirming DTCs, confirm the throttle valve opening percentage and closed throttle position switch condition using the hand-held tester or the OBD II scan tool.
Fig 3: Throttle Valve Troubleshooting Chart
G02590525Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002