Can NOT get trailer lights to work

[tstex]

Have a tandem 20ft trailer that I keep at my farm and is covered. My leasee's heifers ate off the 4 pin connector. Bought a new 4 pin connector [3M1FeMale] and spliced it onto the harness. Have a 2014 F-150 w trailer package. When I went to plug in the 4-pin connector, I first need to plug in my 7-4 pin vehicle to trailer adaptor into my truck. Well, I do recall going over a very steep [unmarked] dip in a farm road about 40 MPH, and the back end of the truck hit the ground in all the bouncing. That was 8-9 mo's ago.

So, when I went to plug in the adapter, instead of a round hole, it was oblong and the adapter would not fit. I finally was able [w force adjustments] to get the adapter into the trucks receptible, then plugged in the trailer connecter: Nothing. my truck also has a single separate receptacle that the trailer harness connector can plug into: still nothing. I unscrewed the white ground wire from the front of the trailer, took a wire brush, got fresh metal on all. Cut off the older exposed wire off the grd and got new fresh strands. Put it all back together: nothing.

Here are some questions:

• Can perhaps a burned out light on the trailer cause a short and prevent the lights from working?
• I inspected all the wiring on the trailer harness and didn't see anything spliced, cut or torn
• Is there a way to test either one or both of the trucks trailer receptacles?
• Every light and function on my truck's front, back and inside works fine. Could a burned out fuse cause the receptacle to fail?

Any questions or things for me to check out? I am all ears. I live 60 miles from ranch, but I can take pic's of my truck if needed. My trailer is remote.

The next time I am out there, I am going to ask one of my nbors to come over and see if I can plug in my trailer to his truck and see what happens. based on those results, I will know if it's my trailer. I have to move some furniture for someone and it involves a lot of turning and in Houston, so functioning lights are imperative.

 

[MossRoad]

Trailer plug testers are pretty inexpensive.

I'd spend the $6 at Autozone and get one of these, plug it into your 7-4 adapter that's on your tow vehicle and see if your getting the proper signals out of the truck before suspecting the trailer.

https://www.autozone.com/test-scan-and-specialty-tools/circuit-tester/p/reese-towpower-4-flat-trailer-wiring-circuit-tester/362960_0_0

 

[Dftodd]

Here's a couple things that come to mind. First verify if the plug on your truck is working.

Turn on parking lights and kick the emergency flashers on.

Then check each pin on there with a test light. You should have two pins that will flash, those go you brake light and flash when turn signal is on. Parking light pin should be on solid. Should also have another pin that is on for 12 volt power to charge trailer brake battery.

If they aren't working. Then it could have popped fuses.

I've had some of those 7 pin to 4 pin adapters go bad after a while as well. So you can test the 4 pin side with a test light as well.

I just had to replace the 7 pin plug on my service truck. They can be purchased at any auto parts store.

You can also upgrade your plug to a 7 pin and 4 pin as well depending on how the 7 pin mounts to your truck. They sell replacements for those as well.

 

[tstex]

Moss and Todd, really great suggestions !!!!

I'm off to get a plug tester and will see what I get and post back...what a great way to determine if it's my truck vs trailer.....thanks again

 

[dodge man]

I guess I’m wondering why a 20 foot trailer has a 4 pin? No brakes?

 

[3 Horse Ranch]

I guess I’m wondering why a 20 foot trailer has a 4 pin? No brakes?

The OP said tandem axle, so it's either a light weight small wheeled snowmobile hauler or perhaps it has surge brakes instead of electric.

 

[tstex]

Here's some answers:

I bought the receptacle tester and none of the lights are coming on when I turn on the lights or engage either signal. So it's my back circuitry or something else. The trailer has no built in brakes. I follow the trucks maximum load capacity w non-braking trailer

Does anyone know what the circuity is called for the back trailer lights? I'm trying to "ID" the fuse box to determine if my fuse is bad. If it's not, then I guess I will need to replace the receptacle(s), yes?

Thank you.

 

[3 Horse Ranch]

I think replacing the damaged receptacle would be one of the first things to do. There would have to be a reason for several circuits to stop working or blow a fuse, perhaps the damaged receptacle has allowed several circuits to ground out.

 

[tstex]

I think I found the problem

The wire assembly that comes from the electrical system will not stay engaged to the trailer adapter area. So none of the back receptacles were getting any power. When trying to attached that assembly, should it click in place or something?

 

[3 Horse Ranch]

The trailer has no built in brakes. I follow the trucks maximum load capacity w non-braking trailer

That would be under 3000# for trailer and load in most if not all states.