boat trailer - running lights don't work

[Scottintexas]

I know this should be easy but I can't get it figured out, 5 pin flat connector, 1994 F350 tow vehicle

I hooked my boat up for the first time in months and my running lights on the trailer don't work. Turn signals and brake lights work fine but no red running light in the tail light assembly or yellow side markers.
I think I saw them flash for a second when my daughter turned it on but now nothing.

A few years ago I changed the tail light assemblies to LED's, ran a ground jumper around the swinging tongue and everything has worked great.

I have power at the 5 pin on the truck side along with all the other pins when they are activated so I feel I've ruled that out.

I tried to hook the 5 pin in sideways with just the ground connected and run a jumper from the hot turn signal into the trailer running lights but it wouldn't activate any of the lights (running lights or other turn signal when those posts were chosen) so I think I'm not doing that trouble shooting method correctly.

I would check the bulb assemblies but they are LED at the rear lights and stock bulbs for marker lights so I can't believe everything burned out at once.

Any ideas what I should check or a better way to trouble shoot it ?

 

[Murf'n'surf]

Make sure you have voltage on the plug pin for running lights.

Double check ground connections. Small corrosion can cause issues.

Take off a running light and test it off of the trailer. Start drilling deeper into your ground and power wire in the trailer harness if the light worked outside of the trailer.

 

[captras]

NOt sure what your tow vehicle is....but I think Chevy has a separate fuse under the hood for stop/turn lights and for running lights. You might check those fuses. If it flashed, good chance you blew that fuse.

 

[itsdgm]

If you have power for running lights at the hitch on the vehicle side. Take a circuit tester with a sharp pointy end and poke through the brown wire behind the trailer connection. If there's power there, continue further back on the trailer. I'd suspect that your issue is somewhere between the plug and where the wire splits down each side of the trailer. More than likely at the swing away hinge where it potentionaly could get pinched.

 

[Scottintexas]

It works now,
When I ran my ground jumper around the swing tongue I connected it at the first marker light.

If all the other lights worked I would think I could rule the ground out as an issue, correct ?

I pulled my splice apart near the trailer 5 pin that was also replaced and it looked fine, I pulled the first marker light and found a lot of nesting material so I think a mouse or bird may have found a nice spot over the winter.

I tested the voltage at the marker and didn't get anything and was about to run a positive jumper to it when I noticed they were now working. I'm not sure if a mouse chewed some of the insulation and grounded it out or if it was my splice but I'm ok with it for now.

Thanks for the input,