3A
Description of 4WD Control System Operation
NOTE:
For transfer control system operation, refer to Description of 4WD Control System Operation .
Air Locking Hub Control System Operation
[A]: Operation [F]: CLOSE 2. VSV2
[B]: 2WD → 4WD [G]: OPEN 3. 4WD indicator
[C]: 4WD → 2WD [H]: 5 sec. 4. 4WD switch
[D]: OFF [I]: 10 sec. 5. Vacuum switch
[E]: ON 1. VSV1 6. A/C cut (When A/C switch ON and blower fan switch ON)
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