I installed bedlights under my bedrails. They are LED's. I have a problem and I'm curious if it's common with LED's. With any type of moisture, they turn on in their own. The switch is off but the lights are on. I flick the switch and I have to do it a number of times and they dim. I have a feeling water is causing the switch to act like it's on.

Has anyone else experienced this?

 

Where is the switch?

 

Sounds like the switch to me as well. LEDs use so little power, the moisture could be conducting enough to light them. Maybe get a sealed switch?
When very cold, my 3rd brakelight on the Ranger will glow dimly, just by voltage induced by backfeed through my tail lights. LEDs sometimes do strange things. All the lights except for heads are LED on that truck.

 

Stake pocket hole for bed extender

 

I would suspect the switch also. As johnday said above, it doesn't take much.

I put LED's under the rails of my bed also and used a rubber booted switch and a plunger switch so I can turn on/off/actuate by tailgate. I've never had an issue with this.

Then again, I have a trifold cover on it so may I have had an issue and just never saw it? lol

 

I also have a tonneau but it still happens once in a while when it's on. Right now it's in the garage due to winter and I don't want it cracking and tearing.

I'm thinking I'll spray the switch with wd-40 to remove the moisture and then some white litheum grease.
I know it's something with the switch, I just was wondering if some others have had this problem.