Toyota Tacoma manuals

Toyota Corolla Repair Manual: Circuit description

Refer to dtc p0120

Dtc no.

Dtc detection condition

Trouble area

P0121 The following condition is met 4 times. After the vehicle speed has exceeded 19 mph (30 km/h) once, the throttle position sensor output value is out of normal range when the throttle valve is closed at 0 km/h
  • Throttle position sensor (built in throttle body)

Monitor description

The throttle position sensor varies its resistance with the angle of the throttle valve. The ecm applies a regulated reference voltage to the throttle position sensor + terminal and calculates the angle of the throttle valve based on the voltage present at the throttle position sensor signal terminal.

When the throttle valve is near the fully closed position, the output voltage of the throttle position sensor is low. When it is near the fully open position, the output voltage is high.

The ecm checks the indicated angle of the throttle valve during stop and go conditions. If the indicated angle (or voltage) in the closed throttle position is out of the specified range, the ecm interprets this as a malfunction in the throttle position sensor and sets a dtc.

Monitor strategy

Typical enabling condition

Typical enabling condition

Stop and go is defined as follows:

Stop and go is defined as follows: stop indicates a vehicle speed of 0 mph (0 km/h). Go indicates a vehicle speed of 18.6 Mph (30 km/h).

Typical malfunction thresholds

Component operating range

Component operating range

Inspection procedure

Throttle/pedal position sensor/switch a circuit range/performance problem
Dtc p0121 throttle/pedal position sensor/switch a circuit range/performance problem Hint: this is the purpose of the throttle position sensor. ...

Inspection procedure
Hint: 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, it is usefu ...

Other materials:

Circuit description
The srs warning light is located on the combination meter. When the srs is normal, the srs warning light lights up for approx. 6 Seconds after the ignition switch is turned from the lock position to on position, and then turns off automatically. If there is a malfunction in the srs, the srs ...

Inspection procedure
1 Check connector Disconnect the negative () terminal cable from the battery, and wait at least for 90 seconds.  check the connection of the combination meter connector and the airbag sensor assy center connectors. Ok: the connectors are connected. 2 Check combination me ...

Inspection procedure
1 Check ignition or starter switch assy Check the ignition switch, as shown in the illustration and table. Standard: 2 Check fuse (ecub) Remove the fuse from the instrument panel j/b.  check the continuity of the fuse. Standard: continuity 3 Check relay (mar ...

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