Install the connectors and vacuum hose

Fig 1: Identifying Vacuum Hose And Connectors

Courtesy of VOLVO CARS OF NORTH AMERICA.

Install:

the connectors on the master cylinder and the power brake booster
the vacuum hose on the check valve.

NOTE: The vacuum hose must be behind the bracket for the ABS hydraulic modulator.

NOTE: There are 2 connectors for the master cylinder on cars with 6-cylinder engines. One is for the pressure switch and the other is for the power brake booster.