P0123
DTC P0123 THROTTLE/PEDAL POSITION SENSOR/SWITCH "A" CIRCUIT HIGH INPUTCIRCUIT DESCRIPTION
HINT:
- This is the purpose of the "throttle position sensor".
- This electrical throttle system does not use throttle cable.
- This throttle position sensor is non-contact type.
DTC Detection Condition:
The throttle position sensor is mounted on the throttle body to detect the opening angle of the throttle valve. Since this sensor is electronically controlled with hall elements, accurate control and reliability can be obtained. It has 2 sensors to detect the throttle opening angle and a malfunction of the throttle position sensor.
The voltage is applied to the terminals VTA1 and VTA2 of the ECM changes between 0 V and 5 V in proportion to the opening angle of the throttle valve. The VTA1 is a signal to indicate the actual throttle valve opening angle which is used for the engine control, and the VTA2 is a signal to indicate the information about the opening angle which is used for detecting a malfunction.
The ECM judges the current opening angle of the throttle valve from these signals input from terminals VTA1 and VTA2, and the ECM controls the throttle motor to make the throttle valve angle properly in response to the driving condition.
NOTE: When a malfunction is detected, the throttle valve is locked at a certain opening angle. Also, the whole electronically controlled throttle operation is cancelled until the system returns to normal and the ignition switch is turned OFF.
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.
- The THROTTLE POS means VTA1 signal as well as the THROTTLE POS #2 for the VTA2 signal.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Conditions:
Typical Malfunction Thresholds Part 1:
Typical Malfunction Thresholds Part 2:
Component Operating Range:
The ECM uses the throttle position sensor to monitor the throttle valve opening angle.
a. There is a specific voltage difference between VTA1 and VTA2 for each throttle opening angle.
- If the difference between VTA1 and VTA2 deviates from the specified range, the ECM interprets this as a default and will set a DTC.
b. VTA1 and VTA2 have each specific voltage operating range.
- If VTA1 or VTA2 is out of the normal operating range, the ECM interprets this as a fault and will set a DTC.
c. VTA1 and VTA2 should never be close to the same voltage levels.
- If the difference between VTA1 and VTA2 is within 0.02 V, the ECM interprets this as a short circuit in the throttle position sensor system and will set a DTC.
FAIL SAFE
If the ETCS has a malfunction, the ECM cuts off current to the throttle control motor. The throttle control valve returns to a predetermined opening angle (approximately 16°) by the force of the return spring. The ECM then adjusts the engine output by controlling the fuel injection (intermittent fuel-cut) and ignition timing in accordance with the accelerator pedal opening angle to enable the vehicle to continue at a minimal speed.
If the accelerator pedal is depressed firmly and slowly, the vehicle can be driven slowly.
If a "pass" condition is detected and then the ignition switch is turned OFF, the fail-safe operation will stop and the system will return to normal condition.
Wiring Diagram:
INSPECTION PROCEDURE
HINT:
- If different DTCs that are related to a different system are output simultaneously while terminal E2 is used as a ground terminal, terminal E2 may be open.
- Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.
Step 1 - 2:
Step 3 - 5:
Hand-held tester
Step 1 - 2:
Step 3 - 4:
OBD II scan tool (excluding hand-held tester)