General Information On Malfunctions In The Brake System - AH42.30-D-2007-01KOA

Model 415, 420, 447, 448, 470, 471, 636, 638, 639, 907, 910 

Wheel bearing play 

Excessive wheel bearing play can influence the measurement of the wheel speed sensors due to wobble.

Tire size 

Malfunctions can occur due to fitting unequal size tires. Therefore always install tires of one size. Fitting summer and winter tires of the same size designation by axle is safe.

Sensor clearance 

A distance between the wheel speed sensor and the sensor rotor that is too large (target: 0.115 mm to 0.935 mm) leads to voltage reduction at a speed of > 5 km/h. Specified value > 100 mV.

Due to this voltage reduction, the anti-lock braking system (ABS) is not able to function as designed at speeds > 3 km/h and is instead only active from > approx. 10 km/h.

Hydraulic/electric connections 

Incorrectly connected brake lines on the hydraulic unit or incorrectly connected electrical connections of the wheel speed sensors can lead to malfunctions in the brake system and thus to a safety impairment.

Corrosion on the electrical connector of the hydraulic unit can lead to ABS malfunctions.