LED Tail Light partially lit?

[AirMiles]

Today I hooked up my 2018 Airstream Globetrotter 27' to my 2019 F250 and noticed four bulbs of the dozen or so on the left LED taillights are staying lit. Two on the right side brightly and one on the far left and right side really dimly. Anybody ever seen anything like this before? They go out when I disconnect the Airstream from the F250. The four bulbs stay lit while connected to the truck with truck turned off and no lights lit on the truck. They go out when the umbilical cord is disconnected from the F250. The taillight stays the same with the Airstream Store/Use switch in either the store or use position.

I can't imagine there's separate wires feeding these four bulbs, but to act this way with some dim, some bright, and some off would require multiple feeds. The running lights, brake lights and turn signals all work properly on the truck and the Airstream when they are turned on. This just doesn't make any sense to me???

[overlander63]

Originally Posted by AirMiles

Today I hooked up my 2018 Airstream Globetrotter 27' to my 2019 F250 and noticed four bulbs of the dozen or so on the left LED taillights are staying lit. Two on the right side brightly and one on the far left and right side really dimly. Anybody ever seen anything like this before? They go out when I disconnect the Airstream from the F250. The four bulbs stay lit while connected to the truck with truck turned off and no lights lit on the truck. The taillight stays the same with the Airstream Store/Use switch in either the store or use position.

I can't imagine there's separate wires feeding these four bulbs, but to act this way with some dim, some bright, and some off would require multiple feeds. The running lights, brake lights and turn signals all work properly on the truck and the Airstream when they are turned on. This just doesn't make any sense to me???

Check the umbilical connectors, and the plug on the truck, for a wire touching another wire.

[BayouBiker]

Individual LED's do not use the full 12.5 Volts so they are hooked in series in groups. So you are getting partial cross over connections from either the tow cable positive or the brakes. The Brake Controller applies a constant low voltage to the brakes that is not enough to actuate the magnetic solenoids but allows the controller to sense the presence of active brakes.

There could be cross connection due to crud in the connection. Clean both with a bit of Electrical connection cleaner or alcohol or brake cleaner but some brake cleaners remove/damage paint so careful with that. Next clean the connection points with vinegar with a bit of salt added until they are a nice brass color again, then thoroughly rinse with water. Connect it again to see if the problem cleared up.

If not check the trailer wiring for a short:

With the cable disconnected ground the negative pin to the trailer frame with a jumper wire (should already be grounded, but you nevver know). Then use a second jumper wire and apply 12 V from the trailer battery to the other pins one at a time and confirm proper operation of each connection.

If all is good here the problem may be in the truck wiring harness or go back and clean the connectors again and carefully inspect it for damage like cracks or bent/damaged pins. If the connectors seem undamaged, you'll have to get a multi-meter and do some heavy duty troubleshooting on the truck wiring.

[bwpaint]

Has it been raining, or have you recently washed your trailer? Similar thing happened to me after washing and I got water in the umbilical connector. Dried out with air hose and solved the problem. Now I make sure my connector is pointed down when not connected to the truck. Hasn't happened again.

[BayouBiker]

Originally Posted by bwpaint

Has it been raining, or have you recently washed your trailer? Similar thing happened to me after washing and I got water in the umbilical connector. Dried out with air hose and solved the problem. Now I make sure my connector is pointed down when not connected to the truck. Hasn't happened again.

If rain, wash or soapy water is enough to cause cross connection, you may want to clean the connector as suggested above, must be some road salt or other crud in there.

[AirMiles]

Thanks for all the suggestions. I think you’re all correct. It was damp and drizzling. I checked all connections and nothing fixed it. So I hooked up to my son-in-laws f250 and everything worked perfectly. So I thought it was my truck. But when I reconnected to my truck everything was fine. Must have been a little short or bad ground. We will keep an eye on it.

Thanks again for the suggestions. Off we go to the Daytona 500!

[AirMiles]

And now I walked back to the truck and the same lights are on again! It just takes a few minutes for them to turn on? It started raining before I walked outside. Maybe it’s the rain. Well I’ll keep trying to figure it out.

[Portage to Caravan]

This exact same thing happened to me, only on the right side lights.
My trailer was sitting in the laneway, on its own, not connected to the TV or 110V. I plugged the 110 in, charged the batteries and the lights went out. I'd meant to post and ask if anyone else had noticed this effect or if it was just me, but never quite got around to it. I have only seen this once and of course now the batteries are in winter storage.

[Rokitman]

Up front, let me say that, to me, electricity is "magic".

3 years of total and complete frustration with the left tail lights and turn signal, several symptoms similar to what you're experiencing. Ours was also intermittent in that it would work fine sometimes, and sometimes not work correctly at all... or not work for a few hours, then work great for a couple days, then partially or not at all the next few. Sometimes a simple jiggle of the 7-way plug fixed it. Sometimes, DW would turn on or off something in the TV during the lights check (turn off the radio, turn off the a/c, turn on the headlights) and the tail light would magically work. Sometimes not. Didn't matter if it was damp or rainy. Had to be extra cautious making left lane changes and turns to the left. Replaced the umbilical plug twice. Replaced the umbilical cord once. Performed numerous continuity checks based on guidance from Forum electricians (Thank You all); results all successful. No satisfaction. Finally gave up, and took it to a dealer... who, after running their tests, replaced the left tail light... no issues with it for the last 2 years. Yes... I'm sleeping well again. Ahmjussayin.

[rmkrum]

Don’t beat yourself up.

Electrical and electronic stuff actually runs on “magic smoke”. The proof of this is that if the smoke leaks out, the gadget quits working immediately. [emoji3][emoji3][emoji3]

Well, it’s a little more complex than that.

I’m glad you got it resolved either way...

[cliffcharb]

LED lights will do that when the board gets wet. Just replace the lights. Most of the reputable manufacturers actually offer a lifetime warranty on their LED lights