Why don't the back up lights work on ford f150 2004?

Answer 1

Well, you have to diagnose in order to figure this out... that's the first part of making any repair. After all, you can't be told or figure out how to repair it if you don't know what's wrong in the first place, correct?
So, start by getting the easy stuff knocked out first. Check your fuses... with the key on, run a test light (might as well go through the entire fuse panel while you're there to see if any others are blown). Fuses check out? Okay, now to the tail lights. Remove the tail light assemblies, remove the bulbs from the reverse lamps, and check them out... are they burnt out? Do they have broken filaments? If so, replace the bulbs. Problem not solved? Remove the bulbs... which the switch in the "ON/ACC" position and the transmission in reverse, take a test light and check for power at the light socket... if you have it at the light socket, reinstall one bulb... if you it light up with one bulb but go out with two, you're looking at replacing the reverse lamp switch. If you have no power period, then you would and diagnose the reverse lamp switch... now, the stuff I work on, we typically just raise the boot above the shift tower and access it that way... but your F150 isn't a semi tractor, so that probably won't work for you. You'll have to get under the vehicle... at the top and slightly to the left of the transmission, you'll see a weatherpack terminal... it goes into the switch... disconnect the weatherpack terminal, and jump the two sides of the weatherpack (effectively bypassing the switch) with a paper clip, jumper wire, whatever works for you... if you have reverse lamps at this point, then the switch will have to be replaced. You just need a wrench to remove it (what size for your vehicle, I'm not certain... again, the stuff I work on is much different) and install a new one.

Answer 2

Could be,

burned out bulbs,

blown fuse,

faulty backup light switch or wiring,