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Toyota Sienna Service Manual: When servicing full-time 4wd vehicles

Toyota Sienna Service Manual / Introduction / Repair instruction / Precaution / 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:

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.

Braking Force Test 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 below.

*: This is to avoid damaging the center differential.

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

(d) On-Vehicle Wheel Balancing

On-Vehicle Wheel Balancing
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.


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.

For vehicles equipped with mobile communication systems
FOR VEHICLES EQUIPPED WITH MOBILE COMMUNICATION SYSTEMS (a) Install the antenna far away from the ECU and sensors of the vehicle electronic systems as possible. (b) Install an antenna feeder ...

For vehicles equipped with traction control (trac) system
When using a 2-wheel drum tester such as a speedometer tester or chassis dynamometer, etc., or jacking up the front wheels and driving the wheels, always push in the TRAC cut ("TRAC OFF") ...

Other materials:

Adjusting the set speed
To change the set speed, operate the lever until the desired set speed is displayed. Increases the speed Decreases the speed Fine adjustment: Momentarily move the lever in the desired direction. Large adjustment: Hold the lever in the desired direction. In the vehicle-to-vehicl ...

Torque Converter Clutch Solenoid Circuit
DESCRIPTION The shift solenoid valve DSL is turned "ON" and "OFF" by signals from the ECM in order to control the hydraulic pressure operation, the lock-up relay valve, which then controls operation of the lock-up clutch. MONITOR DESCRIPTION Torque converter lock-up i ...

Checking tires
Check if the treadwear indicators are showing on the tires. Also check the tires for uneven wear, such as excessive wear on one side of the tread. Check the spare tire condition and pressure if not rotated. New tread Worn tread Treadwear indicator The location of treadwear indicator ...

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