After Engine KA24-012039

CIRCUIT OPERATION
The ECU will substitute the input signals for the air flow meter, engine temperature sensor, intake air temperature sensor and the throttle sensor if the circuits fail. This will allow the vehicle to driven until repairs can be made.
NOTE: The engine will operate at reduced capacity.

Fig. 7 Air Flow Meter Fail-Safe Operation:

AIR FLOW METER MALFUNCTION
If the ECU senses that the air flow meter output voltage is out of the normal range it will substitute the throttle sensor signal for the correct signal. Engine rpm will be limited to 2400 in order to inform the driver that the ECU is in the "Fail-Safe Mode". Refer to Fig. #7 for operating conditions.

Fig. 8 Engine Temperature Sensor Fail-Safe Operation:

ENGINE TEMPERATURE SENSOR MALFUNCTION
When the ECU senses that the engine temperature output voltage is out of the normal range, it will substitute voltage at preset values. Refer to Fig. #8 for operating conditions.

THROTTLE SENSOR MALFUNCTION
When the ECU senses that the throttle sensor voltage is out of the normal range it will substitute a voltage signal at a preset value.

AIR TEMPERATURE SENSOR MALFUNCTION
When the ECU senses that the air temperature sensor is out of the normal range, it will substitute a value of 68° F (20° C).