Back-Up System

Fig. 78 Back-Up Control System:

The back-up system is provided in case there is a malfunction in the ECU's central processing circuit, it also serves as a back-up if the crank angle sensor circuit is open or shorted.

BACK-UP SYSTEM ACTIVATING CONDITION
The back-up operation will function when the following conditions occur:
1. No 120° signal for several seconds or the 1° signal from the crank angle sensor is equal to 0 rpm.
2. The start signal was present for more than several seconds.
3. Battery voltage is above 10 volts.
4. The neutral (M/T) or neutral/park (A/T) signal is present.
5. The computing function of the ECU is judged faulty.
The "Check Engine" lamp will illuminate to notify the driver that the system is operating.

BACK-UP SYSTEM CONTROL FUNCTION
The system will control the following devices or functions under certain limitations:
1. Ignition timing.
2. Injection duration.
3. Fuel pump operation.
4. Idle speed.
5. Power valve operation.
6. EGR operation.

BACK-UP SYSTEM CONTROL CANCELLATION
The back-up operation will cancel each time the ignition switch is turned off. The system will re-activate if the conditions are still present.