Service brake system
 

Here's the scoop. My Brake light comes on and "Service brake system " comes up in the DIC of my 2005 Sierra 4wd. This happens when i brake hard and do not activate the ABS, also happens if i brake hard enough to activate ABS and also happens if i spin rear wheels from a light or stop sign. I tested all of this this moning on way to work since it was raining and easy to do all tests .. It does not happen if i brake "normal" and come to stop. Thoughts?

My lights would come on randomly, but especially when it was raining on my 2001 2500HD and it was the antilock sensor on the front hubs. Do your brakes feel good? This was a while ago and the sensor was not available by itself. I would of had to have replaced the hub as well and they were $180 per side. So I just lived with it.

Yes brakes feel fine. Both front wheel bearings have been replaced in the past 2 years and have the ABS sensors in them. The ABS light does not come on at all when this happens and this also happens when it is not raining. I just tested today on way to work. Rotors and pads are less than year old.

Well got home on Friday and found fluid was low and the front right caliper bleed screw was leaking a bit. topped up and tightened up. No more issues. Who'd ah thought.