I have a 91 camry. While trying to install a remote starter I don't know what happened and my light wont come on. Dashboard head lights and parking lights. Everything is fine. Since this was not working I uninstalled the remote starter and I still ended up with no lights. I've been looking for this yellow box in the trunk but there is no such thing. I see the wires coming out from the back seat and to the back tail lights and back side markers but NO SHUCH THING AS A YELLOW BOX. (I took the whole trunk apart) no luck.
So yesterday I started looking at everything again. Fuses are fine relays. Are new bulbs have been replaced and nothing. I was using the needle tester and went to the main switch. There are 3 cables coming from the beginning of the switch I tested all of them 2 of them had electricity running thru and one wasn't. Check this out tho. When I put one end of my tester to the chasis of the car and poked with the other end to every single cable I noticed that the head lights turned on but no tail lights. Well that was one cable. The other cable same thing happened I saw electricity runing thru and the tail lights came on. The third cable had no electricity at all but nothing turned on still. What do you guys think the problem might be. HELP PLZ!!!!!

First off, welcome to AF. I moved your post to a separate thread since the circumstances are a little different and changed the title to suit.

The stop lamp failure module is located on the driver's side, mounted to the rear inner fender in the trunk, underneath the carpeting/cover.

You can also check the wiring harness to the trunk lights for cracked or broken wires. These become brittle and fatigued from years of use.

Finally, Check the taillight control relay that is located on the backside of the fuse block hidden behind the change pocket by the driver's left knee.

Hope this helps!