Toyota Celica 2005 Repair Manual page 302

DTC P0121
CIRCUIT DESCRIPTION
Refer to DTC P0120 on page DI−96.
DTC No.
After the vehicle speed has been exceeded 30 km/h (19 mph)
even once, the output value of the throttle position sensor is
P0121 out of the applicable range while the vehicle speed is between
30 km/h (19 mph) and 0 km/h (0 mph).
(2 trip detection logic)
MONITOR DESCRIPTION
The throttle position sensor varies its resistance with the angle of the throttle valve. The ECM applies a regu-
lated reference voltage to the throttle position sensor positive terminal and calculates the angle of the throttle
valve based on the current voltage 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 8 times or more, the ECM inter-
prets this as a malfunction in the throttle position sensor and sets a DTC.
MONITOR STRATEGY
Related DTCs
Required sensors/components
Frequency of operation
Duration
MIL operation
Sequence of operation
TYPICAL ENABLING CONDITIONS
Item
The monitor will run whenever this DTC is
not present
Malfunction criteria and its threshold are met 8 times from once GO is judged until STOP is judged
GO: Vehicle speed
STOP: Vehicle speed
2005 CELICA (RM1131U)
DIAGNOSTICS
Throttle/Pedal Position Sensor/Switch "A"
Circuit Range/Performance Problem
Detection Item
P0121
Main sensors/components
Related sensors/components
Continuous
8 times or more
2 driving cycles
None
Minimum
30 km/h (18.63 mph)
−
301
− ENGINE (1ZZ−FE)
S Throttle position sensor
S ECM
Throttle position sensor rationality
Throttle position sensor
Vehicle speed sensor
Specification
See page DI−3
Trouble Area
Maximum
−
0 km/h (0mph)
DI−103
DI383−15