Troubleshooting
DTC P0123 Throttle/Pedal Position Sensor/Switch "A" Circuit High InputHINT: This is the purpose for the "throttle position sensor".
CIRCUIT DESCRIPTION
HINT:
- This Electrical Throttle Control System (ETCS) does not use a throttle cable.
- This throttle position sensor is a non-contact type.
DTC Detection Condition:
The throttle position sensor is mounted on the throttle body. It detects the opening angle of the throttle valve. This sensor is electronically controlled and uses Hall-effect elements, so that accurate control and reliability can be obtained. The throttle position sensor has 2 sensor elements/signal outputs: VTA1 and VTA2. VTA1 used to detect the throttle opening angle and VTA2 is used to detect malfunctions in VTA1. Voltage applied to VTA1 and VTA2 change between 0 V and 5 V in proportion to the opening angle of the throttle valve. There are several checks that the ECM performs to confirm proper operation of the throttle position sensor and VTA1.
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 driver inputs.
Reference (Normal condition):
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.
- THROTTLE POS means the VTA1 signal and the THROTTLE POS #2 means the VTA2 signal.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Conditions:
Typical Malfunction Thresholds:
Component Operating Range:
The ECM uses throttle position sensor to monitor the throttle valve opening angle.
a. There is an expected specific voltage difference between VTA1 and VTA2 for each throttle opening angle.
- If the difference between VTA1 and VTA2 is incorrect the ECM interprets this as a fault and will set a DTC.
b. VTA1 and VTA2 each have a 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 VTA1 is within the range of ±0.02 V of VTA2 the ECM interprets this as a short circuit in the throttle position sensor system and will set a DTC.
FAIL SAFE
If the ETCS (Electronic Throttle Control System 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 infection (intermittent fuel-cut) and ignition timing in accordance with the accelerator pedal opening angle to enable the vehicle to continue at a minimum 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 DTCs related to different system that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.
- Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, as well as other data from the time when a malfunction occurred.
Step 1:
Step 2:
Step 3 - 4:
Step 5:
Hand-held tester
Step 1:
Step 2 - 3:
Step 4:
OBD II scan tool (excluding hand-held tester)