1. Remove the vacuum hose..
2. Verify that air can be blown from the power brake unit side of the vacuum hose towards the vacuum pump side, and that air cannot be blown in the opposite direction.

If there is any malfunction of the inner check valve, replace it together with the vacuum hose as a single unit.
Vacuum Hose Removal/Installation
Vacuum Pump InspectionRelay And Fuse Block
Purpose
Relays and fuses used by each system are grouped and housed together for
smooth inspection and replacement servicing.
Function
Relays and fuses used by each system are grouped and housed together.
Construction
Installed in the engine compartment.
...
Clock Spring Removal/Installation [Standard Deployment Control System]
CAUTION:
If the disc on the combination switch is deformed or has foreign material
adhering to it, performance of the steering angle sensor may be reduced, causing
abnormal operation. When handling the clock spring, be careful not to deform
the disc and make sure there is no foreign ...
Horn
Purpose, Function
The horn sounds according to the horn switch operation.
Construction
Installed to the inside of the front grille.
The diaphragm is vibrated to apply vibration to the air and produce sound.
Operation
1. When the horn switch turns on (1), the ho ...