Relay is stuck on

[Gorman]

I have a problem with my ud. The relay for the left turn signal on the trailer plug is stuck on. Not blinking, just on. The signal on the truck doesn't do this. What's got me totally confused is that it does this with the truck off. I have a feeling this is gonna drain the batteries.

 

[Tom Dunlap]

Some thing that I've found with odd trailer light things is that the ground is more than likely the problem.

Start at the hitch plug and clean the contacts on the truck side too. Is the ground on the truck plug wired back to the battery or wired to a bolt/lug on the frame?

Start checking the lights to see if they're jumper grounded to the frame or does the ground wire come all the way back to the connector?

Finding leaking electrons is MUCH harder than finding leaking fluids. You need to know how to use a multi-meter to find the leaks in an electrical system...not the puddle on the floor!

You might try changing bulbs or at least cleaning the contacts.

 

[monkeylove]

Can I assume you checked the relay it self? Being a turn signal I belive they are normally open when there is no power. It could just be burned into the closed (on) position. Not good but better than chasing electrical issues.

 

[monkeylove]

They can difficult to check by hand sometimes but most good auto parts places can usally check them.

 

[Gorman]

It's not the bulb. I tracked it to start at the truck plug with a test light. It's on even with the truck off and the truck light is off. If it was the relay I would think the truck light would be on too.

 

[TreeLogic]

Was gonna say that a bad ground connection (usually corroded metal that needs shining up) can cause some crazy stuff, but it looks like Mr Dunlap beat me to it...x2

 

[Gorman]

You know what?!?! I just remembered I put two new batteries in it not that long ago, it might be a loose negative lead.

 

[monkeylove]

That does sound like a ground issue. If the trucks plug tests okay, then try a continuity test from the trailer plug to the trailer. Maybe...I hate trying to find electrical gremlins. Good luck.