2002 Trailblazer Wiring Problems

i have had wired problems with my 2002 trailblazer my transmisson started slippin from 1st to 2nd, the brake and abs light came on, speedometer is off, can not set the cursie control and this all started happening at once? i have replace the ingintion switch put new brattery in it and had the transmisson rebuilt and looked over by a 2nd guy and said the tranny looks good and working the way it should. but the problems are still there had a few different mechanics look at all have ran out of ideas. i love the truck but im ready to drive it into a tree lol. i need some help or some new ideas of what could be wrong with it