I have a 2003 trailblazer, I went to the dealer for and oil and lube, and they changed fluids and told me that the license plates lights were out. So on the way home I bought a couple bulbs... few days later I put them in, when I did, the rear hatch started trying to lock by constantly clicking, so I closed the hatch and everything seemed fine till I opened the hatch and it immediately started trying to lock again, then driving down the road all the warning lights on the dashboard came on and the gauges fell (no oil pressure no water temp), the truck was still running fine (rpm gauge continued to work as well speedometer) but the electric doors and windows would not work, then after a couple of miles , approx. 2-3, everything went back to normal..
I stopped at a friend’s house and put it on a scanner it came back. 0 codes
But then listed all kinds of things like 02 heater, 02 sensor, cant not remember all the listings but it was not giving a good reading. Do you know of any electrical problems in the 03 trailblazers? So that I can know which way to go to get this fixed.

 

Start over, take the bulbs out, if the problem stops be sure they are correct.
Re-insert, examine the wires etc., goodluck if that's not the problem.

 

Do you have any additional circuits possibly branching off of the fuse box under the rear seat? This is a very big no-no with the GMT360 platform vehicles. The power is specifically regulated to the rear fuse box and any additional draws are not handled well, causing some very weird problems.