Trailer light trouble

[Peter simon]

I know this could go in the general forum but prefer answers from boaters with the same boat.
I hooked up my trailer to my 2021 Sierra and the truck recognized my trailer then said trailer disconnected a few times. It worked all last year with the truck.
I took my truck in for service and had then check and everything was functioning. The truck has the trailering package so it will even tell me if a bulb is out.
I had the boat in for service and they said everything on the trailer is working.
I saw some devices where you can plun into the truck and test. Is there one I can plug into the trailer and test the trailer?

 

[HawaiiBreeze]

My two cents:

1. If its a Shorland'r trailer beware the inboard wiring harness. Mine disintegrated inside the frame rails. Junked it and went LED.
2. 9.8 times out of 10 for me it has been grounding problems when the lights did work and then didn't. Once I even pinched a hot wire between the shell of the light and the trailer and after enough movement a hole in the plastic sheath of the wire rubbed through and shorted out. That one was
the hardest to diagnose since everything "appeared normal".

Lastly, if the trailer is using regular bulbs you may have had a leak and the bulb sockets are corroded.

 

[scokill]

100% of my trailer issues over the years has been a ground wire.

 

[Babin Farms]

I have this issue with my truck occasionally and is all my problem is the plug itself doesn't have a good connection when I hit a bump in the road.

Start with the simple things before tearing into something.

 

[WV Hillbilly]

Dielectric grease is your friend on all connections. I know I use waaaay too much most of the time but it helps keep all corrosion away.