LED taillights still stay on

[max7157]

We replaced the existing tail lights with a set of led lights. I noticed the lights remain on one side even if the tow vehicle is not connected. Any suggestions?

[tlsmit1]

An exorcist?

I can't imagine how doing nothing other than changing the tail lights could have produced this change. Did you do any other rewiring?

The tail light wiring should be a direct connection between the bulb and the connector plug for the tow vehicle. You should not be able to power the tail lights from the house batteries. If this is what's happening, something in your signal light wiring is connecting somewhere it shouldn't.

[HowieE]

You need to give us more info. There is no source of power at the tail light fixture that could cause the lights to be on.

Did you change the fixture or just the bulbs? How many wires where involved if it was the fixtures?

[richinny]

also, make/model/year of tow vehicle.

[max7157]

The tail lights on the right side were replaced with LEDs and work correctly. The left side however is a problem. It appeared that after the LED's were installed in the daylight, things looked real good as the lights seemed to work properly. In the evening, it was noticed that the LEDs on the left side were on. (Incidentally, it isn't my trailer). We replaced the LED units with the original standard bulbs and the lights seemed to work correctly. It bothered me and I put a voltage tester on the lines and found very low voltage on the left side when there should have been none when the trailer is not connected to the tow vehicle. I guess that the voltage was sufficient to run the LEDs but was not sufficient for the standard 12 vote bulb. The owner of the trailer is going to continue searching for the source of this low voltage in the trailer.
Thanks for all your interest and help.

[richinny]

if the light was on without being connected to the tow vehicle i would suspect a short in the umbilical cord at the plug or junction box.

[gmw photos]

My vote is for a poor ground somewhere in there. Current is passing thru somewhere you would not expect it, and is getting to that socket. He will have fun chasing that one.

[Skater]

Originally Posted by gmw photos

My vote is for a poor ground somewhere in there. Current is passing thru somewhere you would not expect it, and is getting to that socket. He will have fun chasing that one.

Yeah, that's my thought, too. Especially since they seem to be dim. My problem with a short in the connector theory is that it should affect all of the running lights...but then so should the ground issue. It's very weird that it's only affecting some, if all of the lights work correctly when hooked to the tow vehicle. (Unless we misunderstand what lights are lit - are we just talking about, say, the left turn signals, versus all of the running lights on the left side?)

The incandescent bulbs require more current, so it might not have been obvious they were getting some juice, but LEDs can light up with a lot less current so you're just now seeing a problem that was there before.

[TG Twinkie]

I would start by pulling the fuses (in the trailer) one at a time to see if the lights go out.
But first. Are you plugged in to shore power? If so, unplug and see if the lights go out.
By doing the above, you will eliminate or identify that the problem is in the internal wiring.
If the lights don't go out. The UCord or it's terminal box ( if equipped) would be my next step.
Make sure that all interior lights and equipment are off. If the marker lights come on with anything on in the coach. It could be a ground path problem.

[RickDavis]

Originally Posted by richinny

if the light was on without being connected to the tow vehicle i would suspect a short in the umbilical cord at the plug or junction box.

I agree. LED lights require little current and wet dirt, cobwebs etc in the trailer connector could allow enough current to flow to allow the LED to be on but not a regular bulb.
Assuming you don;t have a molded on connector I would open it and look for wet dirt, little hairy wires etc between the charge line terminal and the terminal for that tail light.

[gmw photos]

Originally Posted by RickDavis

I agree. LED lights require little current and wet dirt, cobwebs etc in the trailer connector could allow enough current to flow to allow the LED to be on but not a regular bulb.
Assuming you don;t have a molded on connector I would open it and look for wet dirt, little hairy wires etc between the charge line terminal and the terminal for that tail light.

Could be, and even though the OP said "tail lights", it might be the turn/brake light circuit for that side. If it's actually tail light, then following Rick's troubleshooting we might see current at more than one socket in the tail light circuit. Which would mean both tailights and all the running lights.
Ain't it fun chasing down electrical gremlins ?

I could bore you with a long story of chasing an electrical issue years ago in an early 80's Oldsmobile, that ended up being of all things, a flaky connection in one of the interior dome lights. That took a while......

[overlander63]

Last year on the forums, somebody else had this exact problem, and it turned out to simply be water in the 7 pin connector where it connects to the tow vehicle.

[gmw photos]

Originally Posted by overlander63

Last year on the forums, somebody else had this exact problem, and it turned out to simply be water in the 7 pin connector where it connects to the tow vehicle.

....aw, you're no fun. We were in the middle of making this a real mystery with all the troubleshooting of Apollo 13.......

[Skater]

Originally Posted by gmw photos

....aw, you're no fun. We were in the middle of making this a real mystery with all the troubleshooting of Apollo 13.......

Gentlemen, failure is not an option!

A lot of it depends on exactly WHICH lights are lit. If it's all of the lights on one circuit (such as all of the running lights, or all of the turn signals on one side, or something like that), then it's more likely an issue in the connector or something simple like that, but if it's just some of the lights on a single circuit, it could be a lot more complex.

[JackDog]

I have a 2013 16' Sport;

I just got back from a 6 day trip and after parking the AS, unhooking and turning on the battery disconnect switch noticed the next morning (still dark) that all the led lights we're very dim but still on (except the left rear tail light).

When I get home tonight I'll check the plug and clean it really good. I keep a coupler cover over the front and stick the plug inside it so that no moisture, dust or other junk gets into it.

I did plug the AS back into the TV and the exterior lights come on just fine. After I unhooked and the lights we're off they started to glow again after about 10 minutes.

I hope its not some expensive electrical problem as it just went out of warranty!

Jack Dog
in So Cal

[Skater]

Originally Posted by JackDog

I did plug the AS back into the TV and the exterior lights come on just fine. After I unhooked and the lights we're off they started to glow again after about 10 minutes.

I'm back to the exorcist solution. Halloween is coming, right?

Seriously, that has to be some kind of short in the connector or something like that. It only takes a minute and a screwdriver to open it, so it's a good starting point. I can't figure out why all but one would come on, though. If it's not in the connector, I'd start looking closer at the light that's NOT on.