Master Cylinder Description

The master cylinder assembly consists of an aluminum body and a plastic brake fluid reservoir. Internally, the master cylinder houses two pistons (one primary and one secondary) and three piston cups. The master cylinder is mounted on the brake booster assembly. When the brake pedal is pressed, the primary piston compresses the volume of the primary chamber, increasing the hydraulic pressure in that chamber. This pressure, along with return spring force, causes the secondary piston to compress the volume of the secondary chamber. The hydraulic pressure in the primary chamber acts on the rear brakes - both right and left. The pressure produced in the secondary chamber acts on the right and left front brakes. On vehicles equipped with the Antilock Brake System (ABS), the master cylinder hydraulic lines are connected to the hydraulic modulator. For more information regarding ABS, refer to ABS System Description in Antilock Brake System.

Reservoir and Cap
The reservoir is attached to the top of the master cylinder which is located under the hood on the left-side of the bulkhead. The reservoir is made out of see-through plastic and is marked with the MAX level on the outside.

Fluid Level Switch
The brake fluid level switch is located in the master cylinder reservoir. If the master cylinder fluid level becomes too low, it will cause the BRAKE indicator to illuminate. This will alert the driver that a low fluid level condition exists in the master cylinder reservoir.








The LSPV consists of a lever and a load sensing spring. The spring senses the variations in the vehicle height proportional to load weight. A plunger/valve mechanism inside the LSPV perform the hydraulic pressure modulation.
A chamber with a fail-safe piston monitors front hydraulic brake pressure. In case of front hydraulic brake pressure loss, the fail-safe piston releases the plunger/valve mechanism, canceling hydraulic pressure modulation. This allows full master cylinder hydraulic pressure to apply the rear brakes.
The LSPV assembly is bolted to the vehicle frame. The LSPV lever is connected to the rear suspension upper arm by a bracket and load sensing spring.
As the vehicle is loaded, the distance between the rear suspension axle housing and the vehicle frame decreases. As the LSPV load sensing spring length changes, it applies force to the LSPV lever. The lever then moves, actuating the plunger valve inside the LSPV assembly. This results in increased rear brake hydraulic pressure proportional to the vehicle loaded weight.