ajolliff

I have a 2007 F150 Super crew, with a Swiss Cab High Shell. The third brake light is wired in. That is all that the shell has. Just one wire going from 3rd tail light on shell to green wire under driver side. Currently with the headlight switch in Automatic, headlights, and tail lights work but the dash lights and instrument lights do not. If I move the switch to park or full on the heaed lights and dash lights work but the tail lights do not. I have had it at the Ford dealer for this once before. They replaced a distribution box, then said that the only way the could get the lights to work was to unwire the shell. I took the truck to the place that the dealer recomended and had the shell wired back in. 3 months later same thing. It was an intermittent problem at first but now they have gone off, and not returned. I do not understand how the camper shell wire for the 3rd brake light, (one wire) is screwing up the dash lights and the tail lights. Any suggestions?????

crackhead

I have a 2002 F-250 with the same exact issue.. Headlight switch to auto-Taillights, but no dashlights.. Switch to normal - dash, but no tail.. What was your fix??

lariat 04

I had the problem in my 02 GT but it was for trailer lights, had everything screwed up. It just ended up being a bad crimp, a short or something. Maybe you have a bare spot somewhere or a bad crimp as well.

crackhead

So what ended up being the fix?

squirrelyyy

Have to agree my boat trailer has wreaked havoc usually a short somewhere in the wiring in the trailer. I would check the shell for shorts nothing else makes sense

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07 F150 4x4 Lariat Screw 6'5" dark stone metallic,pueblo gold metallic,tan interior,auto spring 2" leveling kit,305 65 R18 bfg all-terrain t/a ko,af1 cai,cat back magna flow si/do 3 1/2" tips right side exit b/4 right rear,sct x3 tuner vmp custom tunes,Recon smoked taillights & smoked 3rd brake light,Recon projector hd's 8000k HID ,pioneer avic z110bt infinity speakers pioneer sub,amp & pioneer backup camera

Bucko

Take a volt/ohm meter (you can get a cheap one at Radio Shack or the like for under 10 bucks). Set it to ohms "x10" scale. Put the black probe to a good ground (I would not trust the trailer wiring ground; it may be the culprit). With the red probe, insert the tip in each female connector of the trailer wiring (under the left side bumper). If the volt/ohm meter goes to zero on any of the leads, there's your short (to ground). You may have one of the circuits shorted to another (I.E. brake/turn signal, parking lights to one another). Check that too.

I'm going to guess it's the wiring in the shell. The manufacturer most likely ran the wire along the shell body, and it chaffed somewhere to the truck bed metal. You could remove the bulb in the shell's third brake light (it would "open" that circuit) and see if the problem goes away. Then you'd know for sure it's in that wiring.

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"Give someone an answer, they learn for that day; introduce them to the search function, they learn for life"

2005 F150 STX Regular Cab (4.2)
2000 H-D FLHT

lariat 04

Just had to re-crimp the plug two of the wires were accidentally crimped together. It was an add on plug and it just laid flat on the set of wires going to one of the break lights and the part that you actually crimped just poked through both sets of wires, and one of the poke through prongs was touching two wires out of the set.