My back up lights are not working.They just stopped working one day. Have a new boat with trailer hooked up recently. Thought that had something to do with it. Anyways. It isn't the bulbs, the fuses are good and the fuse slots all have power, it isn't the relay it has power but when i put truck in reverse there is no power to the socket for the bulb. I have been told it might be the "back up switch" but when i search for the part on several sites it does not exist in my 2004 F-150 5.4 v8. There is one for 2005-2006. Anyone able to help?

 

Auto or Standard trans?

If you've checked the 15 amp fuse in the central junction box, and if an auto trans,, it could be the transmission range sensor (DTR) on the side of the transmission.. Check the wires at the DTR connector and you should have 12v power 'IN' on the LB/PK wire with the key in RUN,, then when reverse is selected the circuit power should be 'OUT' on the BK/PK wire as well..

If a manual trans,, the reverse lamp switch is mounted on the driver side of the trans,, more towards the front of the trans about where the bellhousing would meet the main trans case.. If you look at the 'fill plug' on the L/side of the trans, the reverse switch would be to the left and up.. Same wire colors for the manual trans.. To prove out the reverse switch 'and' check for power distribution IN/OUT of the switch you can first unplug the connector and check for 12v current on LB/PK wire, reconnect the connector and when shifted to reverse the power should be through both wires LB/PB and BK/PK as above.

 

it is a auto trans. thanks for the help as soon as i can i will check that out.