Fail-Safe Function

The fail-safe function maintains driveability if trouble occurs in the vehicle speed sensor, throttle sensor, inhibitor switch, or any of the solenoids.

Vehicle Speed Sensor
A dual speed sensing system is used. The speed signal is taken from the transmission (output shaft revolution sensor) and also from a sensor built into the speedometer. If one sensor system fails, normal control can be maintained with the other system.

Throttle Sensor
If the throttle sensor becomes faulty, throttle will be set to the predetermined position.

Inhibitor Switch
If two signals are input due to inhibitor switch failure, the vehicle can be driven under this priority: D > N (P) R 3 2 1.

Shift Solenoids 1 and 2
If trouble occurs in either solenoid, both are turned OFF and the vehicle is made driveable in the 3rd hold range. If both solenoids fail, the mechanical hydraulic circuit is used.

Shift Solenoid 3 (Overrunning clutch)
If the overrunning clutch solenoid fails, the solenoid is turned OFF. The overrunning clutch will engage so that the engine brake is applied when reducing vehicle speed.

Duty Solenoid A (Line pressure)
If duty solenoid A fails, the solenoid is turned OFF and line pressure is raised to maximum to enable vehicle operation.

Duty Solenoid B (Lock-up)
If duty solenoid B fails, the solenoid is turned OFF and lock-up is released.

Duty Solenoid 3 (Transfer)
When duty solenoid C becomes inoperative, it turns OFF. Maximum oil pressure is applied to the transfer clutch so that power is always transmitted to rear axles (direct-coupling AWD).