When Servicing Full-Time 4WD Vehicles

WHEN SERVICING FULL-TIME 4WD VEHICLES

The full-time 4WD SIENNA is equipped with the open center differential system.

If incorrect preparations or test procedures are used, the test will not only be unsuccessful, but may be dangerous as well.

Therefore, before beginning any such servicing or test, be sure to check the following items:
- Whether wheels should be touching ground or jacked up
- Transaxle gear position
- Maximum testing vehicle speed
- Maximum testing time

CAUTION:
- Never accelerate or decelerate the vehicle suddenly
- Observe the other cautions given for each individual test

a. Before Beginning Test
This vehicle does not have a center diff. lock mode or 4WD (Normal) Mode to allow only the front or rear wheel to be rotated.

The test method for this vehicle is different from that for vehicles equipped with the center diff. lock mode or 4WD (Normal) Mode, so make sure to use the correct test method.




b. Braking Force Test
(Vehicle Speed: Below 0.5 km/h or 0.3 mph)
When performing low-speed type brake tester measurements, observe the following instructions.
1. Position the wheels to be tested (front or rear) on the tester.
2. Shift the transaxle shift lever to "N" position.
3. Idle the engine, operate the brake booster and perform the test.




c. Speedometer Test or Other Tests
(Using Speedometer Tester or Chassis Dynamometer)
When performing test at high speed or high load, use the methods shown.

NOTE:
- Confirm that the vehicle is securely immobilized.
- Never operate the brakes to drive the wheels or stop them suddenly.




d. On-Vehicle Wheel Balancing
When doing on-vehicle wheel balancing on a fulltime 4WD vehicle, to prevent the wheels from rotating at different speeds in different directions from each other (which could damage the center differential), always be sure to observe the following precautions:
1. All 4 wheels should be jacked up, clearing the ground completely.
2. The parking brake lever should be fully released.
3. None of the brakes should be allowed to drag.
4. The wheels should be driven on the wheel balancer with the engine running.

HINT: When doing this, be careful of the other wheels, which will rotate at the same time.

5. Avoid sudden acceleration, deceleration and braking.
6. Carry out wheel balancing with the transaxle in D position.