The abs light and brake light is on the speedometer does not work until i hit 30. the tempature gauge fluxuates from 210 to almost the 260 and then goes back down to 210. What is causing these issues?

be looking for operating voltage in the system with the car off and running..should be stable and no higher than 16.5 it may be fluxuating some.. a sign that the regulator is going out..

not a good idea to do a voltage test on a computer component, it can result in damage to the ECM.
if only the speedometer is not working and the other gauges do work, the first place to start is the speed sensor, it is the most common issues with inoperative speedometers.

Have a factory or professional scanner hooked up , check for DTC'S - diagnostic trouble code's .GM had problem with stepper motors in side the instrument cluster ,model years 2003 to 2006 . Stepper motor's control the gauge needles .
How to repair GM Instrument Cluster Speedometer Gauge Stepper

The ABS an service brake message or probably related , have it checked for code's !

If everything else works ok, the vehicle drives normally, and all the other gauges are working then you may have a bad speedometer servo motor. This servo is what actually moves the speedometer needle to match the speed you are driving at. The cluster would need to come out and be repaired to fix this problem if this is the case.

You should have a speedometer cable that runs from the back of the trani, thru the fire-wall, and into the back oh the gauge cluster.

The brake and ABS light both come on when you are receiving no speed signal. Most likely the speed sensor in the top of the rearend is bad.

it sounds like it is the speedometer cable that goes from the speedometer gauge to the transmission is wearing out.unless you have done one of these before then i would suggest having someone do it for you.

It is your battery. Replace it and you will be good as new.
It has happened to me 2x now.

You may have a faulty electronic speedo unit.

Could be your Speed sensor that would make the abs light come on because its not sensing the speed you are traveling. I have no Idea why when your gas gauge is on empty it won't shift. May be its the speed sensor and it was just happened to do it right when you where on empty. Does the speedometer work right or is it erratic? Let me Know this sound like and interesting problem I would like to work on and trouble shoot. Your ECM may be going too. There is so much going on Its hard to tell. But I would make sure the speed sensor is working properly first, Ok Talk at you soon. Thanks Bear001... Oh Yeah make sure all fluids are up and in good condition