P0303

WIRING DIAGRAM

CIRCUIT DESCRIPTION
ECM monitors crankshaft revolution speed via the crankshaft position sensor and engine speed and cylinder No. via the camshaft position sensor. Then it calculates the change in the crankshaft revolution speed and from how many times such change occurred in every 200 or 1000 engine revolutions, it detects occurrence of misfire. When ECM detects a misfire (misfire rate per 200 revolutions) which can cause overheat and damage to the three way catalytic converter, it makes the malfunction indicator lamp (MIL) flash as long as misfire occurs at that rate. After that, however, when the misfire rate drops, MIL remains ON until it has been judged as normal 3 times under the same driving conditions. Also, when ECM detects a misfire (misfire rate per 1000 revolutions) which will not cause damage to three way catalytic converter but can cause exhaust emission to be deteriorated, it makes MIL light according to the 2 driving cycle detection logic.





DETECTING CONDITION AND POSSIBLE CAUSE



DTC CONFIRMATION PROCEDURE

WARNING:
- 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.
- Road test should be carried out with 2 persons, a driver and a tester.

1. Turn ignition switch OFF.
2. Clear DTC with ignition switch ON.
3. Check vehicle and environmental condition for:
- Indication of fuel level meter in combination meter: 1/4 or more
- Ambient temp.: -10°C, 14°F or higher
- Intake air temp. : 5O°C, 122°F or lower
- Engine coolant temp. : Normal operating temperature
4. Start engine and keep it at idle.
5. Check DTC in "DTC" mode and pending DTC in "ON BOARD TEST" or "PENDING DTC" mode.
6. If DTC is not detected at idle, consult usual driving based on information obtained in "Customer complaint analysis" and "Freeze frame data check".





REFERENCE

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INSPECTION