Description of On-Board Diagnostics

When the failure of a major sensor is detected by the on-board diagnostics, the present control logic provides controls to assure safe operation of the vehicle.


EXAMPLE:
Trouble item
Controls to be provided in the event of trouble



VOLUME AIR FLOW
1. Based on throttle position sensor (TPS) signal and engine speed signal (crank angle sensor signal) Sensor basic driving time of injectors and basic ignition timing is read from the preset map.
2. Idle Air Control Motor fixed at predetermined position, and no idling speed control achieved

INTAKE AIR TEMPERATURE SENSOR
Controls provided on the assumption that intake air is 25°C (77°F)

THROTTLE POSITION SENSOR (TPS)
No additional fuel injection provided on the basis of throttle position sensor signal at acceleration

ENGINE COOLANT TEMPERATURE SENSOR
Controls provided on the assumption that engine coolant temperature is 80°C (176°F) (Even if the sensor signal returns to normal, this control mode is retained until the ignition switch is set to OFF.)

CAMSHAFT POSITION SENSOR
1. Fuel injected into the cylinders in the order 1-2-3-4-5-6 with irregular timing (Provided that no No. 1 cylinder top dead center position has been detected since the ignition switch was placed in the "ON" position)
2. Fuel cut 4 seconds after a failure was detected - (Provided that no No. 1 cylinder top dead center position has been detected since the ignition switch was placed in the "ON" position)

BAROMETRIC PRESSURE SENSOR
Controls provided on the assumption that barometric pressure is 101 kPa (760 mmHg) (sea level).

KNOCK SENSOR
Ignition timing is changed from that for premium gasoline to that for regular gasoline.

IGNITION COIL AND [1][2]IGNITION POWER TRANSISTOR UNIT
Fuel cut for cylinders whose ignition signal is abnormal

COMMUNICATION LINE WITH TRANSMISSION CONTROL MODULE
No ignition timing retard control (overall engine-transmission control) achieved when transmission speeds are changed

HEATED OXYGEN SENSOR (FRONT)
No air-fuel ratio closed loop control achieved.

HEATED OXYGEN SENSOR (REAR)
Only signals of oxygen sensor (front) installed upstream of catalyst are used, and the air-fuel ratio feedback control (closed loop control) is not performed.