Toyota Corolla Repair Manual: Circuit description
Refer to dtc p0120
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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 |
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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
”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
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:
Inspection
1. Intake air flow meter sub–assy
Inspect the intake air flow meter resistance.
Using an ohmmeter, measure the resistance between
terminals tha and e2.
Resistance:
at –20 c (–4 f) 13.6 To 18.4 KΩ
at 20 c (68 f) 2.21 To 2.69 KΩ
at 60 c (140 f) 0.49 To 0.67 KΩ ...
Inspection procedure
1 Inspect transmission wire(slt)
Disconnect the transmission wire connector from the
transaxle.
measure the resistance according to the value(s) in the
table below.
Standard:
Measure the resistance according to the value(s) in the
table below.
Standard (check for short):
...
Inspection
1. Cooling fan relay
Inspect the cooling fan relay continuity.
Using an ohmmeter, check that there is continuity
between terminals 1 and 2.
If there is no continuity, replace the relay.
Check that there is no continuity between terminals
3 and 5.
If there is conti ...