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Home >> Scion >> 2006 >> xA Standard >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine Control System (1NZ-FE) >> SFI System >> 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 >> Description

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: Description

Fig 1: Throttle Position Sensor Circuit Description
G04152889Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

These DTCs relate to the Throttle Position (TP) sensor.

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 V 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.

DTC DETECTION CONDITION CHART

DTC No. DTC Detection Condition Trouble Area
P0120 VTA less than 0.14 V, or VTA more than 4.91 V for 5 seconds or more (1 trip detection logic)
  • Throttle Position (TP) sensor
  • ECM
P0122 VTA stays less than 0.14 V for 5 seconds or more
(1 trip detection logic)
  • TP sensor
  • Short in VTA circuit
  • Open in VC circuit
  • ECM
P0123 VTA stays more than 4.91 V for 5 seconds or more
(1 trip detection logic)
  • TP sensor
  • Open in VTA circuit
  • Open in E2 circuit
  • Short between VC and VTA circuits
  • ECM

HINT:

FAIL-SAFE MODE

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