back up lights do not work on 2004 toyota camry

Sounds like the reverse switch under the shifter is out of adjustment. Here are some directions on how to fix it. Not the best description, but should work if you have any car knowledge. Here it is: Fold down the rear seats, and pull one of the reverse lights out of the socket, and leave it hanging in the trunk. This way you have direct line of sight to see when the bulb is lit. Pry that button thing off that is above the letter P. Underneath is a link to make it possible to shift gears without turning on the car. From the back. pry the trim piece around the shifter off, ( the front has a hinge like pieces.) Pull the trim piece off with P R N D 2 1. Using a magnetic screw-driver, or with extra care not to lose one, remove the four screws that hold the piece below. You might be shifting gears to get better access. Use that linkage under the "button" thing to make it easier. This is where I lost a screw. Remove the light bulb. plan to put in a new one. Careful not to break, the parts are brittle by now. Remove light bulb base by twisting about thirty degrees to the right. carefully lift that piece up but there is no need to remove it. You just want access to what is below it.. Now you see a thing like a plastic gear, with notches for each P, R, N, D, 2, 1. At the back of it (also what would be toward the rear side of the car) there is a single screw over a metal plate. loosen the screw. Think which way it should be adjusted/ move it a little, tighten it back. Start the car, and by looking through the seats to the trunk with hanging reverse lights, see if the reverse lights light up when the car is in reverse. Like I said, not the best directions in the world, but you should get the basic idea of where to look if you plan on fixing it yourself....