I was just made aware that my 3rd brake light, brake lights and turn signals are all completely out, with exception to partial lighting and turn signal on my passenger side light.

How would I go about replacing these? I've looked up a video just to see -- but couldn't find anything. Looking to just do the bulbs if possible.

This is for a 99 Blazer. Thanks in advance!

 

Rear turn signals?

open the trunk/hatch and peel back a little of the weather stripping around where the light housing is. There are two Phillips head screws you will need to take out, and I had to move the weather stripping to do mine. Just unscrew those and the tail light housing should slide out giving you access to the bulb housings. Turn those and replace all your bulbs. You can clean inside the tail lights since you have the bulbs removed, and that is how I found a small crack in one of mine, which caused it to short out. sometimes they are hard to see. I used dielectric grease on the connections before replacing the bulbs so avoid corrosion. then simply retrace your steps and replace everything. real simple.

the third brake light I am not so sure about. I will take a look tomorrow and let you know. I plan on replacing mine anyways...

 

If all your rear lights are out, including your 3rd brake light, which I believe is LED's.. and there is partial light up on the passenger side there is another issue there beyond bulbs. You need to pull the bulbs out and test the sockets for power.

 

First , check the fuses and be sure they are good. Use a VOM to test them. Be sure to check all bulbs as you said, but the chances are they didn't all go out at once. It could be the fuses, the brake stop switch on the brake pedal arm, or the Multi function switch aka the turn signal stalk.