Fail-Safe Function

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 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 hold 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)