How do you change heasdlight bulb on my 2007 trailblazer ss?

Check compression on the misfiring cylinder, these engines burn valves and have valve seat problems. You may have to have a shop diagnose it if you have checked all the easy parts.

if the bulbs and fuse are ok it can only be the switch which u will find close to the brake pedal if u unplug the switch and then bridge out the plug this will bring on the brake lights which means the switch is at fault

You can't

you dont open it they install from the backside.you can go to autozone they should replace it for you for free,if you buy the bulb from them

Remove the tail lamp housing and test for power at the wiring connector. Does the center high mount stop lamp operate correctly? The lamp circuit boards have seen many problems.

make sure there pluged in if so you need to get new ones

It sounds like you have an intermitent shift solenoid failure.This is what would cause your failure. You may possibly have an electrical failure also. I hope this helps.
Thank You,
Roy

If the service light is on in your TrailBlazer, open the door, turn the key to ignition position and push the accelerator pedal 5 times, the service light will flash. flash your high beams and you're done.

OPEN THE TAILGATE AND REMOVE THE SCREWS THAT GO SIDEWAYS INTO THE LENS. AFTER THEY ARE OUT, CAREFULLY PULL THE ENTIRE LIGHT ASSEMBLY TOWARDS THE BACK OF THE TRUCK. THERE ARE TABS THAT HOLD ONTO RUBBER INSERTS. AFTER THE LIGHT IS OUT, TURN THE SOCKET OF THE BULB YOU ARE REPLACING AND PULL THE BULB STRAIGHT OUT. HOPE THIS HELPS YOU. PLEASE KEEP ME POSTED. THANK YOU FOR AN HONEST RATING AND FOR USING FIX-YA. GOOD LUCK

did you check the fuse's and or relays.