trailer lights-don't work

[daredevil]

Have a friend coming over with tester tools. Will rule out the ground on the trailer & go from there. Really appreciate the help & tips. I NOW know what to look for & what to do.
Cheers & good fishing!!!!!!!!

[REW]

Daredevil,
When I run into an intermittent problem like this, I want a permanent solution.

Go and purchase a new plug for the truck and install it using appropriate splicing methods.

When you pick up the new receiver plug for the truck, also pick up a new trailer end that fits the same round connector. Cut off all of the wires from the new trailer end plug. Then, have a little rubber maid box to keep the plug for the truck. Fill the holes in the end of the trailer end plug with grease. Then, when not using the trailer, insert the dummy plug with its grease filled holes and put it in and out of the vehicle end a couple of times to insure that all gunk is off of the connections and then leave it in place to insure that the end of the receiver is plugged at all times with the grease coated and hole filled holes in the plug. The grease provides and air tight, moisture tight seal for the plug and you will never have a connection issue again, as long as you are faithful in keeping the hole filled - either with the trailer plug, or with the dummy plug. No open hole, and no corrosion down the road.

If you think that the grease will retard a good electrical connection, there is no worry. As you insert the dummy plug into the truck receiver plug, the grease gets wiped off of the connection, and provides and excellent seal with the residual grease piled around the ends of the connector to insure a water proof seal on the plug to the truck receiver connector.

Give it a try and I expect that you will be well satisfied with the results. When, not using the dummy plug keep it in the rubber maid or equivalent box to avoid getting the grease spread around the vehicle. A bit messy perhaps, but 100% both short term and long term effective.

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Also, be sure to do the reverse with your trailer connector. In the same box as the storage for the dummy plug for the truck, also carry a cap for the trailer to cap the end of the trailer connector when it is not being used. If you don't have anything else, just pick up a box of plastic snack bags and a bag of #64 rubber bands. Then, anytime that you disconnect the trailer, pop a snack bag over the end of the trailer electrical connector and secure a rubber band around the bag and the wiring harness plug to insure that the plug stays dry and free of dirt and debris. A slight hassle perhaps, but worth it when you don't have any electrical gremlins running around to give you lighting fits.

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p.p.s.
Here are some covers for the 7 wire round connectors to help with your problem:

https://www.etrailer.com/search/7+Pin+Connector+Cover

and:
https://www.amazon.com/WirthCo-20081...SCZE6NAY84XCGS

https://www.amazon.com/POLLAK-11761-.../dp/B00AO71LNE


https://www.amazon.com/CURT-58150-Ve...0679273&sr=8-2

https://www.amazon.com/GR-Innovation...a-571778811017

A tester to keep in the truck to check the integrity of the truck wiring and the truck connector, before hooking up the trailer:

https://www.amazon.com/CURT-58270-Ve.../dp/B001EOWQY4