Defective switch, switch not adjusted, blown fuse
There is a switch in the transmission (manual) and I believe also automatic that triggers your backup lights when you move (change gears) into reverse. If the switch (in the transmission) does not touch (trigger) the backup light switch; or if the switch is not working; you will not have any reverse lights. Also , if you have had any changes in your transmission due to lifting the body, or changing the original transmission; the lever that triggers the switch may not be able to come in contact with the backup light switch in the transmission. If you have this switch replaced by a garage it may run around $160 for the switch and another $100 to $200 for labor. If the transmission does not trigger the backup light switch in the first place ,due to changes in the transmission, or a body lift; then changing the switch will not make any difference; the backup lights still will not work.
Try checking the neutral safety switch. This switch is the one in automatic transmissions that makes the backup lights "flip" on when going from park to drive as you go through the gears. When my neutral safety switch shorted my backup lights stayed on constantly.
The backup light switch is mounted on the transmission casing.
replae backup light switch on transmission
Either the switch that turns the backup lights on is out of adjustment, or has failed in the on position.
There is a backup switch in the gearbox. When you shift into reverse, the gear box switch contacts the switch and lights the white reverse lights. If you find that the reverse lights don't work it could be that the switch is not being triggered by the mechanism inside the gearbox. This is providing that everything else is working; wiring,bulbs,etc.
You would have to literally run a wire from the battery through a fuse and then to a toggle switch and then on to the backup lights, this will only function when the switch is on and will have nothing to do with the transmission being in reverse. This is essentially the same as putting a toggle switch across the transmission mounted switch (assuming the transmission switch is not shorted).
Yes
Check the fuses Check the backup switch Check the wiring - make sure that there is good contact.
Check the backup light switch.
If you look at the drivers side of the transmission were the shifter linkage hooks to it you will see an electrical switch behind it. That switch controlls the backup lights among other things.
check reverse light switch on transmission.