towing lights problem

[kooba]

Need some help. I have a F-150 and am having touble getting my trailer lights to work. Heres the problem. I have the male connecter that shows the lights right off of the truck. When the headlights are off on the truck everything works,even when I hook up the trailer. When I turn my headlights on, only the running lights work and no blinkers or break lights. What could be the problem? I checked fuses under the hood and back wire hookups to the female end and everything seems to be ok. Any ideas.

[bigb56303]

make sure that you have a good ground fron the truck frame to the trailer frame, i had a similar problem with my suburban, it might not have a good ground and it will work funny, you can use anything to test it before buying anything jumper cables or any wire just make sure you have a good ground, then if thats the problem make it permanent hope this works for ya

[Giant_Jackpot]

Ground problem................

[Jeremy airjer W]

Kooba, does this happen with or without the trailer hooked up? If it only happens with the trailer hooked up then I would agree that there is likely a ground issue with the trailer. Do the vehicles brake lights and turn signals still work when the trailer ones don't?

[kooba]

This happens when the trailer lights are not hooked up to the truck. I have the connector that lights up when the blinker,brakes,taillights are on. Everything works great untill I turn the headlights on the truck. Then only the tail lights work but no blinkers,brakes. What could be the problem?

[Jeremy airjer W]

Is this a factory trailer wiring or aftermarket? Do the brake lights and the turn signals still work on the truck with the headlights on? What year ford? Is this a four way connector?

If the lights on the truck work but the lights on the connector don't work and it has an aftermarket wiring setup I would suspect the aftermarket wiring.

If the above is true and it has a factory trailer package than knowing the year would help.

Sorry for all the questions but the more info we get the easier it will be to narrow down the possibilities

[Macgyver55]

The first thing I would do if you have the "inline T connector" is to remove it and plug the factory harness plugs back together and see what happens. I've run into these before that are corroded internally but look fine otherwise.

[Jeremy airjer W]

I was also leaning towards a t-connector but without knowing what he has for a setup it makes it hard to narrow down a single component.

[kooba]

Blinkers and tail lights still work on truck with lights on but not down on trailer tow. Not sure if it is factory or aftermarket, I bought it used. The ford is a 2000. The connector is a 7 round to a 4 flat. Wires are all hooked up correctly. When I first found the problem, I noticed under the hood their was no left turn fuse and also one of the fuses was blown for the tow package under the hood. Put new one in. I'm thinking its the ground, what can I do to fix the ground on the truck?

[Jeremy airjer W]

Now I'm kind of thinking your adapter has gone bad. Of course I forgot the diagram at work but I do have something for you to try. This will at least tell us if the 7 way is supplying what it should.

With a test light connected to a good ground and the running lights turned on and the four way flashers also turned on check for power at the tail lamp, right turn/stop, and left turn/stop pins of the 7 way connector. If all of these are functioning correctly then I would check the ground of the 7 way by carefully placing one end of the test light on the tail lamp pin and the other end on the ground pin, the test light should light up. If it doesn't or is dimmer than when you tested the other pins then I would suspect the ground is bad on the 7 pin connector. If it lights up then I would suspect a bad 7 to 4 adapter.

Hope this helps!