hello my 08 yukon 240000+ miles running good laundry list of expenses but its a great truck.
the traction controll light is on and more often the brake indicator on dash comes on with the ding ding ding and after awhile it goes away.
fluid is good brakes feel great so what does that red light mean ...also a also a pump activating sound is comming from second row seats or maybe even the doors if thats possible ?i also notice the pumping sound does coincide at least occasionally with the brake light comming on..i just replaced that big$ battary about4000 miles ago i would hope they would of looked at that but guesse ill have to double check that...
also it now started throwing codes im trying to atatch a picture of them and the reduce engine power is comming on.

 

I know the brake pads last a long time on these Hybrids but is it possible at 240k miles that the brake warning light is for the wear indicator on the pads?
Maybe take it in for a tire rotation (if about ready) and get them to check the brake pads while they have the wheels off?
On the pumping sound I have no clue but if you have not cleaned the inlet screen and fan wheel on the Hybrid battery cooling system I would do that just to eliminate it as the source of the sound. Took me about an hour to clean mine the other day, really not a big deal at all. Note: I found that the previous owner had installed some Weathertech second row floor liners that were completely blocking the air inlet slots at the base of the seats!
Here are a few pics.

cooling fan intake metal grate about 1/3 blocked?

Small shop vac with brush adapter works great

That's right I chopped up the Weathertech floor liner obviously not designed for a Hybrid HO!