trailer light porblem

[picksbigwagon]

Drove back from Belle Plain friday afternoon with no trailer lights, but the running lights came on wehn I turned on the headlights. There is power on both sides of the plug in area. I have the LED lights on the back so I know I didn't blow them out or a bulb....what is my next step here? new wiring harness?

[Northlander]

1st check the harness under the vehicle. I just had to replace mine. It was all full of road salt etc. and was bad. I wish I would have cheched it 1st but did new wiring harnesses at the trailer and truck thinking the old looking ones were bad.

My dad always said start at the truck and work back down the trailer. Its funny how Im 40 and still not taking dads advice.

[Rost]

If you own a Ford, make sure to check the fuses under your hood. Ford has separate fuses for running lights, brake lights, and blinkers.

[marine_man]

I'd do what Northlander is reccomending, as well as make 100% sure you have a good ground... 50% of all trailer problems are usually a poor, or no ground. Make sure the white wire on the connector for the trailer is connected to a good ground, and likewise on the vehicle. Then, verify your grounds on your lights.

marine_man

[picksbigwagon]

we tested the wires from the truck at the plug, all running good current, we tested the wires on the trailer side of the plug, and they seemed to running okay, the side orange running lights work as well

could my white ground wires on the tail lights be bad????? I am really thining that this is a wiring at the trailer problem, but I will start over at the truck and it is a Mecury Mountaineer, so I will look at the ford part as well

now that I think of it, one of the lights was out last fall when I took it down for storage, now I am out two lights.....both tail lights, both LED fully sealed submergeable lights..........and I thought installing the new trolling motor was frustrating

[marine_man]

It very well could be the individual light's ground wire... but... you said you checked the current on the lights at both the vehicle and the trailer... did you verify that the ground was working correctly as well? One way to do that if you're using a test light is to put the aligator clip for the ground on the little prong on the vehicle side and see if you get power on the taillights, turn lights, etc... that will verify that it's working on your vehicle... then clamp the aligator clip onto whatever the white wire on the trailer is connected to and check out the power on the vehicle... if you get good readings on both you've completely eliminated any grounding problem there.

I'd definately investigate the individual light's grounds after that...

marine_man

[Muskieguy]

Hey Picksbw....

I have the same problem you have. Side running lights ok, but no tail light on one side. Please post when you figure out what the problem is. I will do the same.

Muskieguy........

[picksbigwagon]

I was going to post last night, but I didn't want to look like a fool, but I will since you are asking.

I knew I had power on the trailer side of the plug and I knew I didn't blow out my LED lights. So I started at the tail lights and before I cut the wires and re-did them, I looked at the way I had installed my ground wires.

I looked back at the directions I had kept when I got my led lights, and they said to put a washer between the ground area (trailer, behind the light) then the ground wire with loop, then a lock washer and a nut. I didn't think it made sense then and I still don't think it makes sense to do so, but I followed directions. Well, I got rid of that washer, cleaned off my ground wire loop with some steel wool, put on the lock washer and the nut and I had lights. Did it to the other side too.

I always keep some steel wool in my boat for cleaning connections or in case I need to start a fire in an emergency, so I would take a look at the way your lights are grounded, take it all off, scrub the area where the connection is to be made, clean the wire, and the hook it all up......

Like I said, I felt pretty ignorant when I finally figured it all out.

[Muskieguy]

Not sure why you would feel like a fool...you fixed the problem and it was a tough one. I appreciate your help! I will try your advice tonight, clean up the group around the tail light area and give it a shot. I don't have LED but the bulbs look just fine...so I figured it was a ground issue.(since I checked the fuses in my Ford Expedition)

Thanks for posting. I will post tomorrow with my results.

Muskieguy.....

[picksbigwagon]

yeah, do the ground first but I would also run a little steel wool around the light contact too, who knows what go in there. If you are going to replace the lights some day, spend the money and go with LED, they are pretty nice

[Muskieguy]

Just a quick follow up to my problem(no lights to the right rear tail light)....it was caused by 2 problems. Bad ground, which was causing the running lights not to work. Bad filament in the bulb with 2 filaments (even thought both looked ok). For any ground, make sure the area is clear of corrosion, and #2...make sure the ground connections are TIGHT. The bolt was just a little loose, just a little..meaning a 1/2 turn which made it super super tight, and everything worked great.