Master Cylinder
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The brake master cylinder has a brake master cylinder fluid control valve, mounted in the rear outlet port (except dual rear wheel and 9600 GVW E350 vehicles), to limit hydraulic pressure to the rear brakes during normal braking. On speed control equipped vehicles, a speed control deactivator switch is mounted at the front end to act as a redundant safety device. See Figure. The brake master cylinder reservoir is equipped with a fluid level sensor to detect low brake fluid level. The fluid level sensor will provide a ground path to light the brake warning light.