if youre having problems with the abs, then there shouldnt be any reason to even mess with the pcm. they should be looking at the ebcm (electronic brake control module). and your gauges and shit would probably be a bcm (body control module) issue. I personally wouldnt take any legal action, and heres why. Pretty much everything thats going to be done to your car is going to be free because of your warranty. if you hire a lawyer, you're going to take it in the ass due to legal fees, and its going to be a waste of time. Id start talking to the service manager first, then to the director of operations of the dealership. if they provide no solution, talk with the owner of the dealership. and if nothing happens, file a complaint with gm and find a new dealership to go to. give them bad scores on their warranty surveys you get. i would drop your car back off, and tell them you want some type of loaner vehicle you can drive until they fix yours. i'd also mention that you nearly died as well.