6-1-52 ENGINE GENERAL INFORMATION AND DIAGNOSIS (SFI FOR G13)
Throttle
position
sensor
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To other sensors
DTC P0121 THROTTLE POSITION CIRCUIT RANGE/PERFORMANCE
PROBLEM
CIRCUIT DESCRIPTION
DTC DETECTING CONDITION POSSIBLE CAUSE
D After engine warmed up.
D While vehicle running at specified engine speed.
D No change in intake manifold pressure (constant throttle opening)
D Difference between actual throttle opening (detected from TP sensor)
and opening calculated by ECM (PCM) (Obtained on the basis of
engine speed and intake manifold pressure) in larger than specified
value.
: 2 driving cycle detection logic, continuous monitoring
D TP sensor malfunction
D High resistance in the circuit
D ECM (PCM) malfunction
DTC CONFIRMATION PROCEDURE
WARNING:
D When performing a road test, select a place where there is no traffic or possibility of a traffic accident
and be very careful during testing to avoid occurrence of an accident.
D Road test should be carried out with 2 persons, a driver and a tester, on a level road.
1) Turn ignition switch OFF. Clear DTC with ignition switch ON, check vehicle and environmental condition for:
– Indication of fuel level meter in combination meter: 1/4 or more
– Altitude (barometric pressure): 2400 m, 8000 ft or less (560 mmHg, 75 kPa or more)
– Intake air temp.: between –10_C and 80_C (14_F and 176_F)
– Engine coolant temp.: 70_C, 158_F or higher
2) Warm up engine to normal operating temperature.
3) Increase vehicle speed to 30 – 40 mph, 50 – 60 km/h in 3rd gear or “D” range and hold throttle valve at that
opening position for 1 min.
4) Stop vehicle.
5) Check DTC in “DTC” mode and pending DTC in “ON BOARD TEST” or “PENDING DTC” mode.
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