Fail-Safe Function

NOTE: A fail-safe function is provided to maintain driveability even if trouble should occur in the vehicle speed sensor, throttle position 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 speed 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 POSITION SENSOR
If throttle position sensor becomes faulty, the mass air flow signal is backup.

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 > 3 > 2 > 1 >

SHIFT SOL. 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 hold range.

If both solenoids should fail, the mechanical hydraulic circuit is used.

SHIFT SOL. 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 SOL. 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 SOL. B (LOCK-UP)
If duty solenoid B fails, the solenoid is turned OFF and lock-up is released.

DUTY SOL. 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)