Expansion Tank and Brake Fluid Level Switch

The brake fluid expansion tank has internal baffles that reduce foaming during return pump operation.

The expansion tank includes a pick-up tube for clutch master cylinder fluid supply.

The brake fluid level switch is incorporated into the cap. The switch is a reed contact switch.

If the brake fluid is at a sufficient level, the switch is closed and switched to ground.

Fig 1: Identifying Expansion Tank And Brake Fluid Level Switch

Courtesy of BMW OF NORTH AMERICA, INC.

If the fluid level drops below a specified level, the reed contacts open and the MK 60 responds by switching off the ASC/DSC functions.

Normal braking and ABS operation is unaffected.