הודעת היצרן לפעולת ABS לקוייה בדגמי אודי (AUDI).

[danniel]

Audi: Improper ABS activation.

 

Audi reports that quite a few of its 1996-2005 models may activate the ABS under light or normal braking. If checking for conventional problems like damaged speed sensors or wires, mismatched tires or out-of-spec speed sensor air gaps proves fruitless, the German carmaker recommends looking for small cracks in the ABS tone wheels because they're prevalent on lots of its vehicles. Depending on the model, the tone wheel can be found at the outer CV joint, at the wheel hub or the inside of the brake rotor.

 

Finding a minute crack in a tone wheel with the naked eye is just about impossible, warns Audi. The best way to check for a crack is with a lab scope hooked up to a speed sensor. A normal tone wheel will show a smooth, round, uninterrupted sine wave that increases in amplitude and frequency as wheel speed increases. If there's a crack in the wheel, however, you'll see a notch or flat spot on the waveform that repeats itself at the same point for every revolution of the wheel. Replacing the CV joint, hub or rotor is the only remedy.

 

Vehicles that are prone to tone wheel cracks are 1996-2001 A4s, 1998-2002 A8s, 1998-2004 A6s and 2000-05 Allroad Quattros.