Antilock Brake System (ABS)

ANTILOCK BRAKE SYSTEM (ABS)

There are a few performance characteristics of the MK25e anti-lock brake system that may, at first, seem abnormal but in fact are normal. These characteristics are described below.

NORMAL BRAKING

Under normal braking conditions, the ABS functions the same as a standard base brake system with a front/rear split master cylinder and conventional vacuum assist.

ABS BRAKING

ABS operation is available at all vehicle speeds above 5-8 km/h (3-5 mph). If a wheel locking tendency is detected during brake application, the brake system enters ABS mode. During ABS braking, hydraulic pressure in the four wheel circuit is modulated to prevent any wheel from locking. Each wheel circuit is designed with a set of electronic solenoids to allow brake pressure to be modulated at each wheel individually. For vehicle stability reasons, both rear wheel solenoids receive the same electrical signal input during ABS. Wheel lock-up may be perceived at the very end of an ABS stop and is considered normal.

During an ABS event, the Integrated Control Unit (ICU) regulates hydraulic brake pressure at all four of the vehicle's wheels.

The hydraulic pressure at each front wheel is controlled independently (relative to the amount of slip at each wheel) in order to maximize the braking force generated by the front brakes. The rear wheels are controlled such that the hydraulic pressure at each wheel is the same and does not exceed the pressure appropriate for the wheel with the highest slip in order to maintain vehicle stability.