Hi I'm Mesha and my 03 Tahoe 4x4 has been causing me stress! Last week the clicker stopped operating door locks and then started making a slight grinding noise from time to time which sounds like its coming from under hood. This week after driving I take the key out and the CDs start to shuffle, then the clock fades and the dome lights dim. I put the key in and turn over... nothing! The only light on in the vehicle is the yellow outline of the engine light on the dash. Nothing works, Even the all lock door button doesn't work. So I take key out turn it over and retry still not starting but now I hear a clicking coming from what seems to be under the front passenger seat. I wait 5-10 mins and try the key again. 1st time this happened today it wasn't too long before all the gauges flick the dome light comes on and the truck fires right up but the clock is reset as if I disconnected the battery. 2nd time I wiggled the battery connections after nothing else worked and got similar result (clock reset again) As a side note the truck has had issues starting sporadically which we thought was just an old worn key until now. Additionally the driver side seat heat comes on but shuts off right away, rear view mirror component don't work right and on-star speakers buzz. Help please!

 

Welcome to the forum...
Sounds like you have a weak battery or poor electrical connection... the battery connections should be snug and clean, I say snug because you can over tighten the connection and crate more problems...
Remove both terminals and clean the connector and battery post....
Also check the ground strap from the engine to the body...
Check the cable from the alternator to the battery...
Check both ends of the negative battery cable for corrosion, replace if any swelling or cracking is found...