# Ford F-150, no stoplight or tun signals on trailer



## Davis31052 (Jun 27, 2008)

Anyone ever run into this before? I hook up the boat trailer and I have running lights, but no stoplights or turn signals, on the trailer only. I replaced the 7way to 4 way plug with no change. I don't believe I'm getting voltage on the right and left signal/ brake terminals. 

I removed the socket assembly and checked the wiring up to the first two plugs along the framerail by the spare tire.  All the wires were good. The fuse in the fuse box under the hood is good and I don't see any other fuses mentioned in the owners manual.

 All other lights work fine except for the signal and brake lights on the trailer. New lights on the boat trailer, and same problem on the utility trailer. What am I missing, anybody???

BTW, 1997 F-150 Lariat with tow-package.


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## BLAW (Jun 27, 2008)

Are the wires on the trailer grounded? 

I had one trailer that did the same thing with my F-150 when hooked to other trailers they all worked.   Grounded wiring and presto all the lights worked. Hope this helps.


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## Gaducker (Jun 27, 2008)

look under the hood on the drivers side on top of the inner fender and there is a fuse block, open it up and look at the right hand side of the block and the 3rd or 4th fuse up will be blown. at least thats what it was on my f350,  97 model


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## Reelcool (Jun 28, 2008)

I wish I could give you an answer but I'm about to blow yalls mind with my problem on my crew cab 2002 f150. I have no interior lights when you open the door none. all fuses are fine... ok heres the crazy part... I have all left side front and back turning signals brakes.etc... on right side, here it is, front blinker works, rear right brake light works when steering wheel is all the way down but no turn signal.. when you let the steering wheel all the way up I have a blinker but no brake light.... how crazy is that....when I hook up a trailer I have no rear turn signals at all..... this is all on the truck..I think its cursed..


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## Snakeman (Jun 28, 2008)

Narrow it down to a truck problem, or trailer problem by checking for voltage at the light receptacle at the back of your truck.  If you have voltage on the terminals for the turn signals/brake lights there, you know the problem is in the wiring for the trailer.  If there is no voltage at the terminals, you know the problem is with the truck.

If it's a trailer problem, (as already suggested) check the ground on the trailer.  If it's a problem with the truck, (even though you said the fuse was good) replace the fuse.  There should actually be a fuse for the left side, and one for the right side, if I remember correctly.  Another problem could be a bit of oxidation on the terminals at the plug, causing a poor connection.  Do your best to clean the terminals with a small wire brush, or in a pinch, scrape them with your knife (it'd be a good idea to turn off the truck while you do this).

The Snakeman


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## Arrowhead95 (Jun 28, 2008)

I had a problem similar to this on my F350 and believe it or not it was because the brakelight that was on my cab was burned out.
Even caused my cruise control to quit working. Wierd but a common problem on the F350 anyway.

Good Luck.


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## Meriwether Mike (Jun 28, 2008)

You probably pinched the wires around the front of your trailer and it is a short. Check your wires carefully.


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## pjohn21 (Jun 30, 2008)

check your fuse box, i have a f150 2005 and had the same problem, you have fuses for all different wires in the tail lighting system


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## fireman401 (Jun 30, 2008)

Look in owners manual and find the fuses for the trailer wiring harness.  Not the same as the ones for the truck's tail lights.  As far as the steering col. thing...sounds like you have some bad wires in the column.  I had a chevy that did the same type of stunt with the headlights low / high beams......just an idea.  Good luck!


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