I have an 07 f150 stx 4x4 . When I shift in reverse fuse 14 blows . I've changed dtr sensor hooked up 10 amp breaker and test light . The test light dims when shifted in reverse. Can't get it to pop the breaker so can't find short with my manager.any suggestions would be appreciated

 

You've got a short circuit to ground on the backup lamp circuit.

The DTR sensor is fairly unlikely to cause this problem. Usually it's a damaged wire harness, connector, or bulb.

Where and how did you hook up the test lamp?

Have you checked the actual bulbs and their adjacent harness?

Checked the reversing lamp relay for the tow package? Auto-dimming rear view mirror? Audio unit?

 

I hooked test light up to short finder which hooks up to fuse panel . Idk where the reverse relay is. Also I don't have a good wiring diagram.

 

Well, that doesn't help any...

 

Sorry , im hooking a 10 amp breaker in place of the fuse in fuse slot .When the breaker pops the ammeter arrow points in the direction of the short . I have until plugged harness to backup lights on framerail. Done a visual on entire harness from the dtr to trailer plugs on bumper . Fuse 14 controls high pressure switch a/c, cruise deactivation switch , backup lights .

 

There's a few things on F14

 

The reverse relay is for the trailer tow adapter and uses fuse 10 to power the circuit on the 7 pin trailer tow adapter.
- The reverse circuit from fuse 14 is triggering the relay coil only, it is isolated from the reverse lamps on the back of the truck.

Owners Manual shows Fuse 10, trailer tow backup lamp relay is PCB1, which is a relay built into the fuse panel ( not serviceable ). Owners manual page 276.

What are the modifications to the truck ?
- please list all, not just the ones that you think would have something to do with the reverse circuit.

What options does the truck have ( Parking aide, dimming mirror, etc )

Has the truck been in an accident ?

Are you sure the breaker is a 10A ?
- Seems a bit confusing that a 10A fuse blows straight away ( implying a short to ground ), but the breaker does not blow.

Did you remove the bulbs and measure the resistance from the reverse circuit to ground at the bulb connector ?
- Need to use a DVM.

EDIT :

This is the 2006 EVTM, which should be 1:1 applicable for the 2006 to 2008 MY trucks. There could be a change in the connector layout. I do not recall any changes with the reverse circuit until 2009 MY ( major changes all around )

 

I bought truck new never been wrecked have never cut a wire or added any accessories . The short finder im using is from napa its a 10 amp breaker in a red tube with two wires coming out of each end it comes with an ammeter that when breaker trips your supposed to be able to move it along wire when it finds short the needle points straight up . I had it hooked up yesterday drove truck down driveway stopped put it in reverse then it popped it won't do it when I want it to do . Its got me confused m haven't tested backup light socket