System Outline

OUTLINE OF SHIFT ON THE FLY SYSTEM





The shift on the fly system switches between 2 wheel drive (2WD) and 4 wheel drive (4WD) electrically by driver's pressing the 4WD switch (push button type) on instrument panel.
This system controls below operations. (Shifting between "4H`" and "4L" must be performed by transfer control lever on the floor.)
1. Shifting the transfer front output gear (Connecting to, and disconnecting from, front propeller shaft by motor actuator).
2. Retrial of shifting the transfer front output gear.
3. Connecting front wheels to, and disconnecting them from, the front axles by vacuum actuator.
4. Indicator on instrument panel.
5. 4WD out signal to other Electronic Hydraulic Control Unit.

NORMAL OPERATION
The motor actuator mounted on transfer rear case is driven by signal from 4WD switch on instrument panel. After complete the connecting transfer front output gear to, or disconnecting it from, front propeller shaft, condition of the transfer position switch changes. The Vacuum Solenoid Valve (VSV) is driven by the signal from transfer position switch and the vacuum actuator connects front wheels to, or disconnect them from, front axles.





TIMING CHART UNDER NORMAL CONDITION

RETRIAL
The motor actuator starts transfer gear shifting after signal from 4WD switch on instrument panel has been received. But the shifting may be impossible in cold weather or under high speed condition. When 2 seconds have passed since transfer gear shifting started and the transfer position switch does not turn on (the gear engagement is not completed), the motor reverses its rotation for 1.2 seconds and tries again to shift transfer gear. This procedure is repeated 3 times in maximum. While this procedure, 4WD indicator lamp blinks by 2 Hz. If the transfer position switch does not turn on after aforementioned procedure has been repeated 3 times, the gear shifting is stopped and 4WD indicator lamp's blinking changes from 2Hz to 4Hz to notify driver that the gear shifting is stopped. This blinking of indicator lamp continues until 4WD switch is returned from 4WD to 2WD.





TIME CHART OF SHIFTING UNDER SEVERE CONDITION (RETRIAL)

Warning at "4L" position: In view of the shifting mechanism of transfer, the gear shifting from 4WD to 2WD at "4L" condition is impossible. Therefore, the transfer position switch can not be turned off by 4WD switch when vehicle is in "4L" condition. In the case this condition continues for 2 seconds, the shifting to 2WD is stopped and the indicator lamp's blinking changes from 2Hz to 4Hz to notify driver of wrong operation.








TIME CHART OF SHIFTING FROM 4WD TO 2WD AT "4L" CONDITION