How do Brake Service Indicator/Sensors work?
 

My '08 X5 3.0si was in for service to replace a radiator and a rear view carmera, which was mulfunctioning. After replacing camera, software was updated or encoded.

When I dropped it off at the service department, front brakes had 6,000km left and rear brakes had 7,000km left. I picked up the vehicle from the service department, and suddenly the vehicle is displaying that front brakes have only 3,100km and rear brakes have 1,700km.

How come they've gone down that quickly?

Do the brake wear sensors and system calculate the service due every time I turn on the engine or do the sensors have two or three stages that triggers warning and display gradually decreasing number between the stages?

Following is a note from my service advisor.

- Regarding the brakes, it has both a wear sensor, and takes input from the driving profile. If the vehicle sees a lot of stop and start driving or lots of short trips (ie parking lot from the drive-through, parking to the shop, shop to the parking lot, parking lot to wash….) It will re calculate the anticipated distance before they are due. You will likely see a change in this over the next few days. -

So, it means it'll go back up to 6,000km and 7,000km in a few days?

Thanks.

On the E70, there are two stages on the brake pad sensor, and the indicator jumps when they contact. In between those steps, the computer estimates brake pad life based on brake use.

I wouldn't worry about it until the last stage trips, and you get a light telling you they are worn out, and it is time to have brake pads replaced. It takes too much energy to try and figure out what the computer is calculating in between, IMO.

Thank you, JCL. I just wanted to estimate it because I am driving the vehicle to Seattle, about 700 miles from where I live, on Dec. 25, and I am going to get brake serviced at a dealership down there as my US-version X5's brakes are covered under US maintenance program but canadian dealers do not honor the program up here. Canadian maintenance program does not not cover brakes anyway, though.