If the fuses and bulbs are okay I would blame the signal switch assembly. They call it a multi-function switch these days.
switch on the transmission which sends a signal to the reverse lights when shift is in reverse......... is shot. You need a mechanic.
In my case, when turning the lights on, the daytime lights turn off, but the taillamps still on. I found that the steering wheel combo switch (turning lights/windshield switch) connector (the clear color one, was excesive hot and the plastic melt. I changed the connector by a junkyard one and it worked. I guess if you don't have one handy, you'll need to fix your old one.
How bout the turn signal indicator switch located in the steering column.
my 98 suburban did the same thing. when i changed my headlight switch that turns them off and on, they started working again.
Probably the flasher unit needs to be replaced. This is an electronic switch which usually mounts underneath the dashboard.
Possible bad switch on the brake pedal? When you push on the brake pedal, it activates a switch, that switch turns on your brake lights. If the bulbs and fuses are ok, check the switch with an ohmeter.
maybe fuse or broken wire between lights and relay
Are you getting power to/through the switch? Sockets grounded? Open wire to the sockets?
your break switch on your break pedal.
either the switch is not working or a wire to the switch is broken
bad fuse or hazard switch
If parking and tailights are working could be headlight switch--rheostat for dimming control could be bad