have you checked the bulbs and fuses
Bad bulbs can be the cause of your reverse lights not working on your 1999 Toyota Tacoma. A problem with the reverse switch or bad wires can also be the cause of your reverse lights not working.
If the reverse lights are not working on a 1999 Chevy Suburban, be sure to check the fuse panel. If all the fuses are in working order, check the wires for any loose connections. Faulty wires can result in little or no light input.
Could be the brake light switch or fuse.
reverse black and red wires
The hooter is not working
The problem is the reverse light switch. It is located on the top of the transmission that should sloved your problem.
get a friend to check them when u have the can in reverse.. or dont start the car and put it in revers and check them urself
it's your reverse back up switch need's to be replaced that's located on the front of the transmission under the air intake piping
Check the brake light switch.
there is no fuse for the reverse lights check the netural safety switch it may be out of adjustment or shorted.
Check the fuses first then check the bulbs.
Are you sure that the dimmer switch is working?