You can't. You need to take the thing to the goddamned dealer. I'm still pissed off about that two months later.

You can change the headlight without going to the dealer. I have the 2005 LS model with the solid chrome (plastic) strip running entirely across the front. Here are the steps: 1. Pop the hood. 2. You should remove the grille. There are 11 clips that need to be popped. 4 along the top, 2 behind the chrome (plastic) in front of each headlight (4), 1 behind the Chevy emblem, and then two along the bottom of the grille. This should pop the front grille off. The only note is to be gentle with the clips behind the chrome (plastic) so you don't crack it. 3. On the top corners of the headlight casings there are 2 clips/flips that you need to pull up. 4. After pulling these up, it should free up the headlight casing. 5. Disconnect the 3 harnesses in the back of the headlight casing to fully remove the unit. 6. Remove the cap on the back of the light you need to replace (low or high beam). 7. Twist the light about a quarter turn counter-clockwise to remove it from the casing and then disconnect the bulb from the wiring. 8. Replace the bulb and follow the steps in reverse to put everything back together. Hope it helps.

I just replaced both low bean bulbs in each head lamp. You DO NOT need to remove the grille. That is a lot of effort and you can easily break the mounting clips or the assemblies they clip to. Here it is step by step with a few warnings and tips. Replacement time - 5 minutes per bulb. It takes longer to read this than do the job, print it up. (WARNING) when handling the new bulbs, DO NOT touch them with your bare hands. The oil from skin will create a hot spot on the bulb and cause it to burn out sooner than it is rated. I touched one that was on and smoke actually came off the bulb! Use either a cotton glove or I used a clean paper towel to handle the bulb. (tip) If only one low or high beam bulb is out, replace the low or high beam partner on the other side or you may be doing this again real soon. 1. Drivers Side. This is the easiest to get to. After opening the hood, right behind the lamp housing there are (2) rubber caps. The outside cap contains the low beam/day running bulb and the inside cap contains the high beam bulb. a. Both bulbs are replaced the same way. Remove the rubber cap, these caps are soft and pliable but when you grab the edges to pull them off, they feel rigid. This is because the rubber cap is pressed over a hard plastic flange so when you squeeze and pull, it can be difficult to remove. If you can’t get a good grip to pull them off - b. (Tip) There (2) clips on the headlamp housing, one is in plan view to the left and the other is under the fender just to the right top of the housing. It’s a little difficult to get to and you may need a flat head screwdriver to pry it up. Pull up on these clips and they will release the housing, but you cannot remove it. This will allow you to pull the housing out a few inches and you can see the edges of the rubber caps. c. Using a flat head screwdriver, just gently pry the cap, once it starts coming off you can remove it with your hand. Reach in and grab the bulb assembly and turn it about ¼ corner turn “counter” clockwise and it will come out. d. Remove the power wire harness that is clipped on. e. Snap the new bulb into the power wire harness (DO NOT TOUCH) the new bulb with your bare hand! f. Gently place it the bulb assembly back in the housing, turn ¼ turn clockwise, it will snap into place, replace the rubber cap, push the housing back into place and press the housing clips back down. g. NOTE: Always put the rubber cap back on, it helps to keep moisture out of the housing. 2. Passenger Side. This is the hardest to get to. Remove the air cleaner cover and filter or you won’t be able to reach the back side of the housing. The instruction on how to remove these items should be in your owners manual. After opening the hood, right behind the lamp housing there are (2) rubber caps. The outside cap contains the low beam/day running bulb and the inside cap contains the high beam bulb. a. Both bulbs are replaced the same way. Remove the rubber cap, these caps are soft and pliable but when you grab the edges to pull them off, they feel rigid. This is because the rubber cap is pressed over a hard plastic flange so when you squeeze and pull, it can be difficult to remove. If you can’t get a good grip to pull them off - b. (Tip) There (2) clips on the headlamp housing, one is in plan view to the right and the other is under the fender just to the left top of the housing. It’s a little difficult to get toand you may need a flat head screwdriver to pry it up. Pull up on these clips and they will release the housing, but you cannot remove it. This will allow you to pull the housing out a few inches and you can see the edges of the rubber caps. c. Using a flat head screwdriver, just gently pry the cap, once it starts coming off you can remove it with your hand. Reach in and grab the bulb assembly and turn it about ¼ corner turn “counter” clockwise and it will come out. d. Remove the power wire harness that is clipped on. e. Snap the new bulb into the power wire harness (DO NOT TOUCH) the new bulb with your bare hand! f. Gently place it the bulb assembly back in the housing, turn ¼ turn clockwise, it will snap into place, replace the rubber cap, push the housing back into place and press the housing clips back down. g. NOTE: Always put the rubber cap back on, it helps to keep moisture out of the housing

how do i change headlightsin a 2005 chevy trailblazer LT

I just changed my driverside bulb on a 2005 Blazer. First thing you should do is look in your owners manual. It is very easy once you see the pictures. 1. Open hood and hook up your prop rod to hold open. 2 Look in hood behind headlight. You will see two curved/bent handles sticking up flush again the piece behind the headlight. Pull straight up on both of these- they should come right out. 3. Grab front of headlight and wiggle a bit. The headlight should pop right out. 4 If you need to figure out which bulb- turn on headlights briefly and see which one is not working. 5 Looking into back of headlight, turn light socket counterclockwise. The bulb and socket should come out. 6. Open clip on side of socket and pull bulb. Replace with new bulb being sure to keep it clean. 7. For a test, turn on headlights briefly to see if new bulb is working. 8. Put bulb on socket back in carefully and turn clockwise to tighten and check to see socket is firmly in place. 9. Put headlight back in until two tabs go back through holes in hood. Put clips (two) back in place and push down. check headlight to ensure it is firmly in place. 10. You've just changed your bulb! Took me about 5 minutes once I figured out what I was doing. I did NOT have to remove the grill or any other screws, bolts or plugs. Also use a light under the hood to see what you are doing.

Just look for a YouTube video on the topic.