Right sidelight works only when taillight doesn't

[Besegen]

When I got my boat and trailer I noticed the right side running light was not working. Since then the right taillight seal leaked and blew the bulb and corroded up. While it was out the sidelight started working fine. I cleaned up the taillight and fixed the seal and bulb and it works fine now but the sidelight again does not. It will only if I remove the taillight bulb. What would cause this? Ground and feed wires reversed? Or bad ground?

I have not taken time to look at it at all yet but plan to later today. Thought I'd see if someone had a quick answer for it before I did. Thanks guys.

 

[beardeddone]

Re: Right sidelight works only when taillight doesn't

I would check the sidelight with and without the tail light bulb with a volt meter to see what is the voltage is, could also be a bad ground somewhere, the most overlooked grounds are at the tail lights on the trailer if they are grounded there.

 

[Besegen]

Re: Right sidelight works only when taillight doesn't

OK. Thank you. I did clean the taillight grounds and the ground surfaces when I fixed that taillight. It didn't change anything. Will check voltage and any other grounds. Also just thought maybe its wired to brake instead of tail. I'm not sure if the brake was applied when I saw it working or not.

 

[BigDfromTN]

Re: Right sidelight works only when taillight doesn't

A bad ground is your most likely problem. IMO.

Check the trailer to Tow Vehicle ground as well.

 

[Besegen]

Re: Right sidelight works only when taillight doesn't

It must have been either something to do with the bulb being real old and/or dirty, somewhat corroded contacts. The old bulb, though it worked when the taillight bulb was removed, nearly fell apart when I took it out. I replaced the bulb and cleaned up the contacts and it works fine now. Funny though, because as soon as it started working the running light on the other side quit. I guess tomorrow I will just go down that side replacing bulbs and cleaning all contacts too and get it all fresh. Thanks guys.