I have a 97 F-150. Stange thing is happening with my trailer lights. When plugged into our camper with the full hookup of trailer brakes, lights, etc., the lights on my camper work fine.

When hooked up to a simple jet ski trailer only the tail lights work. The Jet ski trailer lights are confirmed okay. I used a test meter and the problem is in the truck. I have seen several postings that relate to this same type of problem. All say to check fuses which I have. Anyone have any other ideas. Could it be one of the relays? Or maybe some sort of grounding problem since the lights work when connected to the camper.

Thanks,

WL

 

WL
Since ALL of the lights work fine on the camper it's pretty safe to say there's nothing wrong with the truck and its wiring, I believe the problem is with the jet ski trailer.

Hook up the jet ski trailer to another truck to make sure the problem isn't there (if you haven't done this already).

Are you using the 7 pin connector for the camper and the 7 to 4 pin adapter for the trailer? If you are (and the trailer checks ok on another truck) the problem might be in the adapter itself.

BTW, welcome to F150online.

 

The problem is in the truck. I have actually checked the 7 point female connector on the truck and the only point that has tests okay is the tail light circuit. I'm thinking it may be some sort of ground problem, that when connected the travel trailer I get grounded throught the travel trailer and everything works fine. Without being connected to the travel trailer I get zero..nothing except the tail lights

WL

 

The first thing I would do is make sure the ground wire (white) of the wiring harness on the trailer is securly attached to the trailer frame and that the mounting bolts for the lights are grounded to the trailer frame as well. For the wiring harness ground I like to use an eylet and a drill point (self tapping) screw and attach it to the trailer tongue. Never depend on the hitch for a ground. Why? When you apply the brakes on the truck the trailer pushes forward slightly and the front of the coupler does not make good contact with the ball, and the rear portion of the coupler is usually dirty/rusty/grease covered and does not provide a good ground. During the day when the tail lights are not on, the current from the brake lights will backfeed through the tail lights thus the tail lights on the trailer light and appear as dim brake lights. This is bad enough, but it gets worse, at night when the tail lights are on and you apply the brakes, the ground is lost again, but now the current cannot backfeed though the tail lights because they are powered and the tail lights which were working because they were using the brake light filaments as a path to ground now go out thus resulting in the stopping trailer having absolutely NO LIGHTS.

Before trouble shooting trailer lights, always make sure the ground wire on both the vehicle and trailer harnesses are grounded to the frame then proceed to troubleshoot the lights with the trailer not touching the tow vehicle.

If this doesn't fix your problem let me know and I can tell you how to test the truck and the trailer to isolate the problem.

Good luck,

 

Brent,

The trailor lights work. I have tested them on another truck. How do I troubleshoot the truck?

Thanks,

WL

 

Are you are using a 7 pin connector for your camper and are you using an adapter to go from the round 7 pin connector to the flat 4 pin connector on the jet ski trailer? Since the camper lights work, the promblem has to be in the connection from the truck to the camper. What kind of test meter do you have (ohm/continuity or just voltage)?

 

It sounds like it's a truck problem... if you're not getting juice at the connector, there's no way the lights will work on any trailer you connect to it. Check the fuses... there are three (?) under the hood in the fuse block. They are dedicated trailer stop/turn signal fuses. Sounds like those are probably blown. My parking light circuit had a short on my 97... didn't discover it until I towed for the first time a year after I got the truck! It's possible to have a short, but cover the basics first.

-Joe-

 

'Lightning,
Don't forget to check the trailer fuse panel. Yes, on Ford's full size trucks with the towing package, there is a separate fuse panel for the trailer circuits.

The box is located on the drivers side, to the right (when facing the front of the truck) of the Master Cylinder. These days, most auto parts stores carry the "mini" fuses. Off hand, I can't recall their "proper" name.

I had to find this frantically one night, after I blew the fuse and went to tow a buddy's boat: no marker lamps. Wound up swapping the fuse with the cig lighter fuse. After this, I put together a fuse & lamp kit & keep it in the truck.

Tony