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:

Engine
On–vehicle inspection Hint: inspect these items on a cooled down engine. 1. Inspect drive belt 2. Replace spark plugs 3. Inspect air filter Remove the air filter.  visually check that the air filter is not excessively damaged, dirty or oily. Peplace the air filter if necess ...

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 useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the ...

Bluetooth® phone message function
Received messages can be forwarded from the connected Bluetooth® phone, enabling checking and replying using the multimedia system. Depending on the type of Bluetooth® phone connected, received messages may not be transferred to the message inbox. If the phone does not support the message func ...

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