Trailer light issue?

Does the tractor work,but not the trailer or nothing on right side truck and trailer?

 

The 3 prong light connectors are finicky sometimes and don't make good contacts even if snapped on the light good. See it all the time. I think they corrode or break on the inside of the plastic where you cant see it. I’ve encountered many were just lightly wiggling a wire at the connecter makes them freak out. A lot of cheap ones they sell as replacement pigtails rot rather quickly too.

 

As with trucks, I will say this about trailers

CHECK YOUR GROUNDS​

 

First thing I would do is pull your power cord out. The male pins (on the plug at back of cab, and plug on front of trailer) are slotted in the middle, use a pocket knife to spread em out a bit so they make tighter contact with the female pins on both ends of the cord.

 

Pull the 7 way receptacle out of the front of the trailer. Make sure no wires are touching. Ground will be the larger white wire very top position.

 

Get a test light. With the 4 ways flashing, test your 3 prong cable on the light that is not working. If no signal track it back to where u find signal.. usually from the light it will go into a junction box or something similar to that where your main cable will plug into.

 

Test all pins on your power unit socket with a test light to rule out a wiring issue with the tractor. Next, move to the end of the pigtail while plugged in. Then plug the pigtail in and begin tracing wires on the trailer from there. You'll find it eventually. Test light are ridiculously cheap at Harbor Freight. You can also plug into a known working trailer to rule out pigtail harness or tractor issues.