1. INSPECT BRAKE VACUUM CHECK VALVE ASSEMBLY

(a) Check the vacuum check valve.
(1) Slide the clip and disconnect the vacuum hose.
(2) Remove the vacuum check valve.
(3) Check that there is ventilation from the booster to the engine, and no ventilation from the engine to the booster.
(4) If any fault is found, replace the vacuum check valve.
Removal
InstallationNavigation check mode
HINT:
This mode displays GPS satellite information.
Illustrations may differ from the actual vehicle depending
on the device settings and options. Therefore, some
detailed areas may not be shown exactly the same as on
the actual vehicle.
1. ENTER DIAGNOSTIC MODE ( )
2. NA ...
Removal
1. REMOVE INSTRUMENT CLUSTER FINISH PANEL
CENTER NO.1 (See page IP-8)
2. REMOVE INSTRUMENT CLUSTER FINISH PANEL
CENTER NO.2
3. REMOVE SHIFT LEVER KNOB SUB-ASSEMBLY
HINT:
(See page AX-146 for U151E, AX-146 for U151F)
4. REMOVE INSTRUMENT CLUSTER FINISH PANEL
ASSEMBLY CENTER (See page IP-9)
5 ...
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 ...