Trailer wiring

So I went to Lake Mead this weekend and the ramp I used was so shallow that I had to back into the water really deep. In fact I had to pull in so deep that I have no idea how people launch there if they don't have a lifted truck. Anyways I have a "Extreme" trailer and ever since I launched only one of my brake lights work and none of my other lights work. Does anyone have any experience with this? Could it be the control module? If so, where is it located?

You don't normally have any sort of control module on the trailer. Some tow vehicles have relays that separate the trailer circuits from the car circuits but most just connect directly to the car circuits.

If you have any sort of test equipment the best thing to do is isolate if the problem is in the car or the trailer.

I like working with a test light, which is a device that looks a lot like an ice pick with a clear handle and a wire coming out the back. You connect the clip on the wire to a good source of ground and then probe with the pointy end. These cost less then $10 and are available at most auto parts stores and many hardware stores.

To test, clip the wire to a good metal part (chrome or unpainted) of the hitch, bumper or frame. Take the test light and probe the contacts of the light connector. Find tail lights, left turn and right turn. Note that BRAKES use both the left turn and right turn so if you have turn signals you should have brakes.

If you don't get anything at the connector then the problem is in the car. If you have a vehicle with a factory installed tow package, such as what came on a Ford Expedition or similar, then you may have a set of relays for the trailer. My Expedition has a fuse box under the hood for this feature. It is interesting to note that these fuses are NOT mentioned anywhere in the owner's manual!

If the lights work at the connector then the problem is in the trailer. Check the lights themselves and make sure that they are not full of water. Check the wires all the way back. I have had situations on really poor ramps where the trailer tires fell into a hole, which made the frame hit the ground and crushed the wires underneath.

Rod
I can't thank you enough for the very detailed info! I have an excursion so I'm going to check for those fuses you mentioned and I will get a tester as well. Once again I REALLY appriciate the help!!!

I disconnect the harness from the vehicle before putting the trailer in the water. No chance of a short, no blown fuses.

hook it up to another vehicle=instant answer.

Doug, that's a good idea. The ramp at my home town lake is very well designed and maintained so it didn't even cross my mind.
Good point jeff!

I was the same way until I realized I didn't need the lights on during the day. The trailer doesn't meet the minimum width requirement in OK for lighting. At night I'll accept the risk and connect only to reduce the chance of dinging the boat or trailer. Fortunately the boat shed is only 1/4 mile from the lake so I don't bother hooking up the lights anymore, unless out on the highway.

Daniel - The fuse connectors for your trailer connectors on the excursion are in the panel located under the dash below the driver's left leg. The manual has a diagram for which one to pull out and replace. I had the same issue, and it was fixed with a .70 cent fuse from the parts store.

They also make some electrical connection anti-corrosion stuff. Its at West Marine and is in a yellow can like WD40. Spray it on the connections once and a while and they stay nice and new. Works great, especially if you run in salt

Well the problem is solved and I can't thank you all enough!!! It wound up being a couple different things. I replaced the trailer lighting fuse under the hood (in position 4). One of the brake lights was full of water and shot so I replaced them with some nice led lights I purchased off ebay for $42.00 for the set and I'm back in business. The led's look great and are significantly brighter, like a homing beekin for drunk drivers. I thing I will be unhooking the lights (when launching) from now on to be safe, although the new led lights are have a much improved sealing wire set up. Once again, I REALLY APPRICIATE ALL OF YOUR HELP!!! I hope I can return the favor some time!