Brake Master Cylinder: Description and Operation

Only one master cylinder is available for all applications. A Bosch center valve master cylinder is used.
The only serviceable components on the master cylinder assembly is the reservoir and sealing grommets. The master cylinder itself, cannot be serviced, and must be replaced as an assembly, if found to be defective.
The reservoir is indexed to prevent installation in the wrong direction. The cap diaphragm is slit to allow atmospheric pressure to equalize on both sides of the diaphragm.
The primary and secondary outlet tubes of the master cylinder are connected to a junction block on non-ABS equipped vehicles. The master cylinder primary outlet port connects to the inboard port of the junction block, and the secondary outlet port connects to the outboard port of the junction block. The inboard port of the junction block supplies the right front and left rear brakes. The outboard port of the junction block supplies the left front and right rear brakes.
On vehicles equipped with Antilock Brakes (with or without Traction Control), the master cylinder primary outlet port outlet tubes connect to the inboard port of the Integrated Control Unit (ICU), and the secondary outlet port outlet tubes connect to the outboard port of the ICU.