Tail lights & running lights not working

[Bob and Susie]

Picked up our 5.0 last of August. Sure tail lights were working on way home. When we left to go to Gulf shores couple of weeks ago our tail lights were not working and still cannot get them to burn. TV F-150 we had trademasters install hitch and additional plug in truck bed. Am I missing something simple the brake lights and turn signals all work.

[padlin]

Did you try the original plug under the bumper?

[Bob and Susie]

Sure did, is there a fuse somewhere for only the tail lights and running lights, If brake and turn signals work then tail lights should burn also i would think.

[elongest]

Signal and brake lights are a different circuit from the running/tail lights. If the truck plug is OK, in an E-21 and most other trailers there is a junction box (or a rats nest) where the trailer pigtail ties into the trailer wiring. If you have a bad connection there that will kill all your running and tail lights. You might see a bad connection if you are lucky. If everything looks good you might have a bad pigtail. You will need a multi meter to troubleshoot the wiring if you don't see a bad connection. I don't have a 5.0TA so I can't tell where the junction box is, just follow the pig tail.

Eddie

[padlin]

Noot a great diagram, but it looks like pin 3 on the 7 pin connector is "tail/running lights". As mentions, it could be in the junction box or the connector on the trailer itself. On my trailer the junction box is under the loft, easy access.

[LeonW]

You might try testing the 7pin connector on the vehicle with a 7 pin connector vehicle tester. That would let you know whether the problem is in the vehicle or the trailer. I had a problem with this last summer, but a bit of emery paper on the plugs seemed to fix it.

[Bob and Susie]

Thanks for all help. I will try the ideas. Not real good with a multi meter. The diagram for plug will help also. Where do you get a 7 pin tester

[steve dunham]

I have repaired two similar problems . Both were traced back to where they tied the 7 pin bed cord into the vehicle’s wiring . The connections were not properly sealed and corroded
It was not difficult to fix just time consuming .

[Bob and Susie]

Thanks

[Eggscape]

If you short out the black 12 volt pin and the green tail light pin on the trailer connector the lights should work. (Assuming your inside power switch is on and battery hooked up) If it does then your trailer is ok and your truck is at fault. Fast and easy test with a paper clip.

[padlin]

Don't know if it'll help any, but as Steve mentions, a likely culprit is the connection between the original bumper 7 pin and the addon in bed 7 pin connector. Don't know what Trademasters uses, but this is the install sheet for the one I used, it shows where mine, and maybe yours could be connected in. Just a plug in thing, looked susceptible to water intrusion when I installed mine.

http://www.hopkinstowingsolutions.com/doc/41157.pdf

[Bob and Susie]

Thanks I will try that tomorrow.

[EdColorado]

With an eye towards trying the simplest solutions first, I would give all the contacts a good spray of an electrical contact cleaner.
I like DeoxIT D5 but there are others. It’s expensive but the can will last you forever.

https://caig.com/deoxit-d-series/



Can’t hurt to try.

Good luck

Ed

[gbaglo]

Originally Posted by EdColorado

With an eye towards trying the simplest solutions first, I would give all the contacts a good spray of an electrical contact cleaner.Ed

Seconded.