How to replace 3rd brake light bulb 2007 Toyota Matrix

Piece of cake! On the black plastic, there are two press fit "buttons", one on each side of the black plastic lens cover. Press in the center of each one and it'll pop open so you can get to the red lens. Now, look at how the red lens is attached with tabs. Carefully lift each corner tab and remove the lens. Under the lens is the bulb. Mine was a GE 921 bulb. The 921 number is also imprinted in the chrome plastic housing for an American bulb number. Change the bulb and reverse the process of installing the red lens, then the black plastic cover. It is advised that you test the brakes to test the new light before reinstalling the covers. There you have it.

I did all that on my 2007 Matrix, but now the light bulb is "wiggly" so doesn't work all the time. How can I make it tighter so it would fit properly and work?

If your bulb is wiggly in the socket, then something is probably wrong. These bulbs are fragile and could possibly have been broken. I'd suggest taking the bulb back out and looking both at the bulb and the socket you used to insert it in. Look closely with a flashlight if possible. You should see the problem.

Thank you so much! I just followed what you wrote above and it worked! Saved me from having to be ripped off by the dealership