Electrical/Computer problem?

I have an 04 Envoy XL, 185,000 miles 4.2 V6 RWD Last night I decided to clean the throttle body because truck has been running rough. I also crawled under the truck to check and clean the ground for the abs module, and I also unplugged and checked the harness to the abs module(the ABS & E-Brake light has been flashing on and off). From the time I unhooked the negative battery cable until the time I got everything put back together was roughly an hour and 30 minutes. When I got back in the car to start it, I noticed the Service Engine Soon, Seatbelt, ABS, E-Brake, lights where all on. Also the light on the Traction Control switch is now illuminated and the fuel guage no longer works. I have ran the truck for about 2 hours and drove it back and forth to work today and everything is still the same. Does anyone have any idea what the problem might be?