stupid question - trailer lights

[redneck joe]

but its me and its electrical...

no trailer lights. working just fine last time i checked them on the truck but that is gone now using the car which i used to bring home from MN. only used a couple three times since and the wire stays tucked up in a storage area in the trunk.

to determine if car side just tester pointy thing to the green plug, turn on some lights and stick the other pointy thing into the other holes and look for voltage?

 

[alldodge]

In most cases if none of the lights are working with a 4 pin plug it's the ground (white wire)

https://www.etrailer.com/faq-wiring-4-way.aspx

 

[Pmt133]

I agree. It's almost always the ground.

 

[Alumarine]

This tester is good for testing the 4 wire connector on the vehicle.
This is just an example. They are widely available.

https://www.etrailer.com/Electrical-Tools/Brophy/F4CT.html

 

[tphoyt]

I have had mice chew the wires in the trailer frame several times. Always a good place to
look if tow vehicle checks out good.
And agree on the ground.

 

[Captain of the Double G's]

The most stupid question is the one not asked

 

[Scott Danforth]

Does your truck have separate trailer light fuses (mine does)

 

[redneck joe]

truck is gone, this is car and afternarket added so assuming no. everything worked when i used the truck.

 

[Jeff J]

The exposed pin on the car side should be the ground. Check for voltage at other pins against it. If that works then the trailer ground is the first place to look when nothing works.

I have also had the fixtures lose ground individually along with badly corroded bulb sockets. Maybe the most common failure I see is the cheap clip on wire splices the trailer manufacturers like. Uncommon for these items to all go bad at the same time.

Occasionally I run into a situation where someone has removed the ground wire from the trailer expecting the ball to provide the ground. It will make intermittent contact at best.

 

[Ifishmuskie2]

I always run the ground directly to each light. I just did a trailer. All wires are covered to prevent mice attacks. I use led and don’t unplug when launching.
Use a meter to check vehicle side.

 

[redneck joe]

so appears to be car side. I didn't install so i'll do some digging....

 

[Jeff J]

I always unplug the lights when dunking the trailer. When I was a kid a wet trailer shorted out my Dad’s truck. Later in life I had 2 incidents where a wet trailer shorted. One of those was a wire shorted to the frame and the other was a bad fixture. I pay more attention these days so most problems get found at home rather than at the boat ramp but I still unplug just in case. Newer vehicles may be better protected but burnt wire smells while stranded on the ramp are hard to forget.

Fixtures may have improved some over the years but wire hasn’t.

 

[airshot]

I always unplug the lights when dunking the trailer. When I was a kid a wet trailer shorted out my Dad’s truck. Later in life I had 2 incidents where a wet trailer shorted. One of those was a wire shorted to the frame and the other was a bad fixture. I pay more attention these days so most problems get found at home rather than at the boat ramp but I still unplug just in case. Newer vehicles may be better protected but burnt wire smells while stranded on the ramp are hard to forget.

Fixtures may have improved some over the years but wire hasn’t.

I hear ya, been dragging trailers for over 60 years and can recount many times poor connections got me in trouble. Some time back, I said enough
Is enough. Bought spools of wire so each run would be one solid wire with no connections except the fixture it was connected to. Then used sealed joints by soldering then shrink wrap with silicone grease inside. More time and expense but never another problem. When buying new to me trailers, the first job was a complete rewire. Today with LED lights, no excuse for faulty cinnections....except for vehicle. I always get factory tow packages
even on used vehicles and so far no wiring issues on vehicles. Over the years I gave saw some real doozy wiring jobs...some so bad you can only laugh at them. Do it once and do it right, then enjoy trouble free trailer ing !

 

[Pmt133]

Adhesive lined connectors that are 2 into 1 are awesome.