Operation (2WD → 4WD)
When the transfer is shifted from the 2WD (2H) position to the 4WD (4H or 4L) position, a 4WD “ON” signal (4WD switch “ON” signal) is transmitted to the 4WD control module which then activates VSV2 to apply vacuum in the intake manifold or vacuum pump to the chamber “B” in the hub housing.
When vacuum is applied, the slide gear is separated from the magnet, moves toward the center of the vehicle body and gets engaged with the outer gear. In this way, the front axle shaft and the front wheel hub rotate as one unit.
If vacuum in the circuit fails to reach –36 kPa (–5.22 psi) within 15 seconds after operation of VSV2 due to such trouble as a hole in the vacuum pipe, the slide gear does not operate and the 4WD indicator flashes to warn that the hub is unlocked.
1.
|
4WD control module
|
9.
|
A/C ON signal (if equipped)
|
17.
|
Outer gear
|
25.
|
Slide gear
|
2.
|
ECM
|
10.
|
Intake manifold
|
18.
|
Chamber “B”
|
26.
|
Wheel hub
|
3.
|
4WD indicator
|
11.
|
Check valve
|
19.
|
Piston A
|
27.
|
Spindle
|
4.
|
Transfer
|
12.
|
Vacuum tank
|
20.
|
Magnet
|
28.
|
Front axle shaft
|
5.
|
4WD switch
|
13.
|
To vacuum pump
|
21.
|
Housing
|
29.
|
To opposite side
|
6.
|
A/C switch (if equipped)
|
14.
|
Vacuum control valve
|
22.
|
Spring
|
A:
|
Vacuum circuit
|
7.
|
Vacuum switch
|
15.
|
VSV1
|
23.
|
Diaphragm
|
[A]:
|
For M13A engine model
|
8.
|
Engine revolution signal
|
16.
|
VSV2
|
24.
|
Sleeve
|
[B]:
|
For K9K engine model
|
Operation (4WD → 2WD)
When the transfer is shifted from the 4WD (4H or 4L) position to the 2WD (2H) position, the 4WD control module activates VSV1 and the intake manifold vacuum or vacuum from vacuum pump is applied to the chamber “A” in the hub housing.
As the slide gear is shifted to the wheel side by the vacuum force and disengaged from the outer gear, rotation of the front wheel hub is not transmitted to the front axle shaft.
1.
|
4WD control module
|
9.
|
A/C ON signal (if equipped)
|
17.
|
Outer gear
|
25.
|
Slide gear
|
2.
|
ECM
|
10.
|
Intake manifold
|
18.
|
Chamber “A”
|
26.
|
Wheel hub
|
3.
|
4WD indicator
|
11.
|
Check valve
|
19.
|
Piston A
|
27.
|
Spindle
|
4.
|
Transfer
|
12.
|
Vacuum tank
|
20.
|
Magnet
|
28.
|
Front axle shaft
|
5.
|
4WD switch
|
13.
|
To vacuum pump
|
21.
|
Housing
|
29.
|
To opposite side
|
6.
|
A/C switch (if equipped)
|
14.
|
Vacuum control valve
|
22.
|
Spring
|
A:
|
Vacuum circuit
|
7.
|
Vacuum switch
|
15.
|
VSV1
|
23.
|
Diaphragm
|
[A]:
|
For M13A engine model
|
8.
|
Engine revolution signal
|
16.
|
VSV2
|
24.
|
Sleeve
|
[B]:
|
For K9K engine model
|