lights not working on small trailer

[dwfizer]

ok... when I hook the trailer up to the truck the only light that comes on on the trailer is the passenger side light. it comes on when the lights are on. nothing happens when either turn signal, or break lights are engaged. The connector is a 4 prong. I am at a loss. I don't know where to check to see if the wiring is bad or if it's the bulb. I took the truck to the chevy dealer to have the truck plug checked - every thing checked out fine. Thoughts?

 

[Grub54891]

Start by checking the grounds at each light, and at the tounge where the white wire attaches to the frame. I always tap into that white wire, run it to each light individually. Less problems with a bad ground. from there you will check each bulb connection and put dialectric grease on each one.

 

[dwfizer]

I know this may sound elementary but how do you “check the grounds”?

 

[Grub54891]

You will have a power wire to go to each light. The ground will be one of the bolts that attach each light to the frame. Make sure they are clean and shiney. Here is a diagram to help.

 

[RMClark]

Recommend you buy a multimeter. Basic function meter can be had for less than $10, and once you learn how useful it is, you'll use it for many different tasks. There are tons of YouTube vids (even some good ones!) that will walk you through the process of using a multimeter and how to troubleshoot electrical issues on a simple boat trailer.

Recommend you also rig up a single wire, about 20' long, with gator clips on each end. You'll use this to test continuity of the wires, along with the multimeter. Again, YouTube vids can walk you through this process.

I had the same issues on my trailer last year. Using the multimeter and the continuity test wire, I was able to determine that one side had a broken wire and that both lights needed better grounds (the previous owner cobbled together the lights with the wrong kind of lights for a boat trailer.) In the case of my trailer, there were so many wiring issues that it took me a couple hours of "test a little, fix a little, test a little, fix a little."

 

[mike_i]

Make sure you do have a ground (white) wire and not getting the ground thru the trailer ball.

 

[dwfizer]

got it all fixed! many thanks for the help on this. it turns out that all the wires were good all the way to the lights on the back of the trailer. The internal components of each were corroded and completely shot. I replaced them and have a well lit trailer!!! I should have checked the connectors for the bulbs before making myself crazy chasing shorts in wires! my mistake was that I checked the bulbs (which checked out fine) but never looked at the connector!
bottom line here is that i couldn't be happier that my light problems are gone!