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Old 10-03-2012, 12:59 PM   #31
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Join Date: Apr 2010
Location: Murrieta, CA
Posts: 9,259
My Ride: '94 325iC & '00 323i
Originally Posted by Caden View Post
The brake sensor was disconnected. This would trigger the DSC light, right? They knocked it out when they were balancing the back two tires. If this is the case, how long would it usually take to reset?
The left front and right rear have two sensors, one monitors wheel speed the other monitors brake wear.

In the days of old, people had to -- wait for it -- _look_ at the brakes to see if they were worn out or not. BMW put in a sensor that "looks" for you constantly so you do not need to do an inspection. The Brake Wear warning comes from one of two things, the brakes are worn or the sensor is broken/disconnected. The brake wear will not trigger a DSC light.

The wheel speeds are monitored to prevent brake lock up or uncontrolled wheel spin. If you slam on the brake and lock a tire, the ABS jumps into action to release the brake pressure to that tire so it can turn -- the idea is that a tire that is turning can be aimed in a new direction while a tire that is skidding will continue on its path regardless of where you attempt to get it to go -- and if the car detects wheel spin, then it will apply the brake to that wheel and reduce the application of throttle.

Since there is a brake wear sensor and a wheel speed sensor both at the right rear corner, I suggest taking that tire off and inspecting the wires to these sensors, and inspecting the brakes at the same time. It is possible that the brakes just happened to wear out at the same time as the tire service, and it is also possible (probable) that the tire service disturbed the sensors.

In any case, the best course of action is to go back to the tire store and take all four tires off and look at the brakes and check the condition of the wires that lead to the wheels. The second best course of action is to blow the tire store off and do this at home.
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