Troubleshooting
P0120 - Throttle/Pedal Position Sensor/Switch"A"Circuit MalfunctionCIRCUIT DESCRIPTION
DTC Detecting Condition:
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- 1.0 V is applied to terminal VTA of the ECM. The voltage applied to the terminals VTA of the ECM increases in proportion to the opening angle of the throttle valve and becomes approximately 3.2 - 4.9 V when the throttle valve is fully opened. The ECM judges the vehicle driving conditions by this signal output from terminal VTA, and uses it as one of the conditions to decide the air-fuel ratio correction, power increase correction and fuel-cut control etc.
HINT: After confirming DTC P0120, use the OBDII scan tool or TOYOTA hand-held tester to confirm the throttle valve opening percentage.
Wiring Diagram:
Step 1:
Step 1(Continued) - 4:
Step 5 - 6:
Step 7:
INSPECTION PROCEDURE
HINT:
- If DTCs P0100, P0106, P0110, P0115 and P0120 are output simultaneously, E2 (sensor ground) may be open.
- Read freeze frame data using the TOYOTA hand-held tester or OBDII scan tool, as freeze frame data records the engine conditions when the 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.
CHECK FOR INTERMITTENT PROBLEMS
TOYOTA hand-held tester only:
By putting the vehicle's ECM in the check mode, 1 trip detection logic is possible instead of 2 trip detection logic and the sensitivity to detect open circuits is increased. This makes it easier to detect intermittent problems.
1. Clear the DTC.
2. Set the check mode.
3. Perform a simulation test.
4. Check the connector and terminal.
5. Handle the connector.