brake fluid 2006 Safari

i am a somewhat proud owner of a 2006 alll wheel drive safari that over the course of the summer has been losing brake fluid and is now picking up the pace. there is nothing obvious as to where it is going, but the strange part is that when the fluid gets low the service engine light will come on and remain on until fluid is added. the brake light or a.b.s. has never come on and brasking seemns normal. any and all help would be greatly appreciated ....sam

The caliper pistons travel out of the caliper when the brakes are applied. As the pads wear, they get thinner and the piston needs to travel farther to take up for the wear. When this happens, brake fluid is drawn from the master cylinder reservoir and into the caliper to compensate for the worn pads. If the reservoir is low, and there are no leaks, the pads are worn.

thank you for your advice and it does make sense, but i am still in a quandry as to why the check engine light comes on each time the fluid is low and stays on until the fluid is topped up. this makes no sense to me at all. i pulled the pads off the front and found the drivers side with about 50%wear[normal] and the passengers side almost to metal. ther was no sign that the caliper was sticking, although not much else would cause this uneven wear. in any case i replaced the front pads and will keep an eye on it as i am really not much wiser. if anyone has any ideas let me know and if not thank you for your help so far sam

If the check engine light is on there is a trouble code stored. get it read with a scan tool and maybe it will make more sense than guessing about it. it could be a coincidence like a O2 sensor triping the light, but you wouldn't know with out a scan and assume the low brake fluid level is causing the problem. Might not even be related problems