Fail-Safe Function

The fail-safe function maintains driveability if trouble occurs in the speed sensor, throttle sensor, [1][2]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. Even if one sensor system fails, the vehicle can be controlled normally with the other sensor system.

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

[1][2]Inhibitor Switch
If two signals are inputted due to inhibitor switch failure, the vehicle can be driven under the following priority. D N P R 321

Shift Solenoid 1 and 2
If trouble occurs in either of solenoids 1 and 2, both solenoids are turned OFF, and the vehicle is made driveable in the 3rd range.
If both solenoids should 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 will be 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 C (Transfer)
When the duty solenoid C becomes inoperative, it turns OFF. This causes maximum oil pressure to be applied to the transfer clutch so that the power is always transmitted to rear axles. (Direct-coupling AWD)