The brake limiter is a valve which is attached to the braking system of a vehicle alongside the master cylinder, and is used to regulate the balance of the front and rear brakes and protect against pressure increases in the hydraulic system.  The brake limiter can adjust the force of the service brakes on the axle, meaning that in slippery road conditions the wheels will not lock, and so preventing skidding.  It does this by stopping the flow of hydraulic fluid to the upper pistons of the brake callipers.  The brake force can be restored to its full capabilities quickly to deal with any other braking requirements.

If the brake limiter is damaged, you may find the rear wheels locking up easily. You may also notice a warning light on your dashboard.  It’s also possible to see a hydraulic fuel leak, which could indicate damage to one or more of the brake components.  If accompanied with spongy brakes or a brake pedal which is to the floor, this is more likely to be a failure of the master cylinder than the brake limiter.  Brake issues should be repaired as a matter of urgency.