A few little glitches that began a couple of weeks ago have now become big issues. In the last 3 weeks my brake peddle has gone to the floor at low speeds (backing out of my driveway; approaching a red light). The brakes came right back and there was no other problem. THEN my ESC and ABS lights came on a couple of times while driving, and went away just as quickly. Oh yeah, there were only 1300 miles on the clock. I took it to a local dealer (not where I bought it). They found nothing wrong and off I went. Two days ago the lights went on and have since stayed on all the time. Hitting the ESC button does nothing. The DIC tells me to service the ESC and ABS. I called my (purchase) dealer and made an appointment for this Monday 3/10 (They are arranging for a loaner for me too).
As if those iSSues weren't enough; yesterday I ran out of gas with my guage reading 1 line below HALF a tank!! I put some gas in the tank and went home. This morning when I started the car (barely 4 gallons in the tank), the guage needle was reading low, but within minutes, the needle moved UP to 1 line below half a tank again.... Stay tuned for further developments

 

Wow my gas gauge is doin the exact same thing right now, so far they have already replaced the fuel level sensor and reflased my computer, still not fixed.

 

Considering you have an 08 and Onstar is standard, why not hit the blue button and have them run a diagnostic check while your driving?

 

I was haulling SS on the freeway and when i finally slowed down my doors made a locking sound.

try seating the fuses in the two fuse boxes
everything including the brakes is all electrical issues
so try the box because reflashing the comp wont do it

 

LR tire sensor flashed a warning for me this morning going to work (have 1500 miles). It stopped reading the pressure, and then 5 miles down the road the sensor was working again, but the warning light remains on. Tire pressure is good though. If it's on when I leave work Ill have to hit the dealership tomorrow to fix that, and look over the brakes.... I have to pump them hard to stop in reverse; feels like they struggle to grab.

 

agreed, check fuses. If it continues you more then likely have a faulty BCM. TBSS's had this issue when they first came out, and a new BCM took care of it.