last year i developed the random doors locking and gauges dying.this only happened when i pressed o the brakes.replaced the battery cables and all was good.til 2 weeks ago.it's back.thought maybe a ground issue so cleaned the firewall ground ,under door ground and added a couple grounds.still does it,BUT i found whats doing it.if i press on the brake just enough to light up the brake lites its fine but if i press the pedal a little farther i get a click and the abs light lites up and the gauges start dropping to 0,if i let up quick gauges come back and abs goes out.i guess my question is what does the partial pedal activate?the abs unit?

 

well did a little more digging and thought maybe it's the brake lite switch so unplugged it.still got the clicking and it still killed the gauges,so got digging farther and the click was coming from the adjustable pedal motor,so unplugged it and cured my issues.so got digging some more and found a tsb(sb-10043829-6448)loss of hi speed GMLAN communication intermittant no crank,IP gauge fluctuation,intermittant door lock cycling,intermitant chimes and various warning lites.all of which i have.so now i just need to dig in but at least i know where it's at.