Help with trailer wiring

I have a Zieman trailer I modified to fit Hobie cradles. But for some reason the brake and blinker lights won't work. So I am pretty sure it isn't my truck (2010 F-150). I use an adapter that converts a 7 pin to the flat 4. It also lights up showing power is running to the trailer. However when I connect the trailer the brake lights go on when I open the truck door. Nothing happens when I hit the blinkers hazards or brakes. Any ideas where to start?

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Vegasvec
2015 Pro Angler 17t
Lowrance Elite 5 Chirp
Zieman Trailer w/ Cradles

I would start by picking up one of these testers. They plug into the vehicle wiring harness and will help you isolate whether the problem is with the vehicle or the trailer wiring.

If the problem is with the trailer, it is usually a grounding issue and sometimes it's easiest to just rip out the entire lighting system and start over from scratch rather than trying to search out the bad ground.



sm

I'd start with making sure you've got a good ground at the trailer. Grounding issues can make them do some pretty strange things! My '02 F-250 has had trouble with the ground at its factory trailer light connectors, so check for ground there as well.

Dave

you can use a 12 volt battery to check you trailer wiring. neg to ground and pos to each of other 3 pins,
one for running lights one for left turn and one for right turn. i have found miss wired adapters. if brakes go on
when you open door it sounds like problem with truck..not positive of that though good luck

What are you pulling it with, You may have relays and fuses under your hood that are blown or not installed (Comes with Towing Package in many vehicles)

Sounds like an adapter problem. Trailer wiring is pretty simple; yellow wire is left blinker/brake, green is right blinker/brake, brown are running lights, and black (sometimes white) is ground.

The only issues that typically come up is when a vehicle has separate blinker & brake circuits, which requires a solid-state adapter to convert to the 4-wire trailer lights. However, I'm not sure how the Ford 7-pin plug is wired (I'm assuming it's a factory-wired F-150).

I wouldn't think the interior light circuit should be going to the 7-pin connector?


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One of my most bizarre electrical problems turned out to be a dual contact bulb in a single contact socket (or was it vice-versa). It was done by the dealer on a used Jeep I bought and it was doing really weird things like the radio wouldn't work if the headlights were aff but the horn didn't work if the lights were on.

Neither myself or nor the Dealer couldn't find the problem after numerous visits. The dealer was tired of me yelling at them after a week of unsafe night driving (no horn) and they were ready to buy it back when I took it to my regular mechanic, who traced it to the bulb in the rear in about 5 minutes flat with a basic electrical meter. Truly shows the value of experience.

I had issues with my trailer as well. Someone installed non-submersible lights and of course the first time I dunked it pop went the bulbs. After figuring out why I had no working trailer lights I installed new bulbs. I still had a constant "on" on the right side, like the brake was being pushed. I cut my losses and bought submersible LED lights from Autozone and rewired the trailer. I think they were around $50 and it took me about 45 minutes to wire everything up. Haven't had any issues since.

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2015 Hobie Tandem Island Hibiscus
"Third Normal Form"

• Trampolines
• Hobie cover
• Davis Spar Fly
• Kayakbob's Sprayskirts
• Spine Board Hakas

I always unplug my trailer before I launch and recover, so there is no power to the bulbs. Even if they are submersible, I figure the cold water against hot bulbs isn't good.

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Yet another Bob!
"Firefly" - 2012 Hobie Getaway with wings and spinnaker
"Icebirds" - 1974 Skeeter iceboat
Too many canoes and kayaks

Yeah... this one makes no sense. The dome light circuit could not lite the trailer lights unless the adapter is configured / wired to the wrong circuit. Factory installed or other?

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Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

My F250 has the parking lights go on when I open a door. If trailer plug is plugged in the lights would come on as well>

The park lights should come on when the door is opened. Industry standard is that you'll have a yellow/brown for the left side and green/brown for the right side. As mentioned above, brown is the market light and is powered when you open your door. The ground is very important. Many people feel the ball is a good enough ground. That's totally incorrect. You must have a solid ground on both the tow vehicle and the trailer.

Here's a great site to see the correct wiring (bottom image for 4-wire system): http://www.hopkinstowingsolutions.com/d ... _codes.pdf

I just finished a day of trouble shooting why my left turn/brake light would not function although the running lights did.
Found that two shrink-fit connectors on the yellow wire had corroded to the point of an open circuit. Cut out both connectors, re-spliced with a better crimping tool & shrink fit connectors that were correctly sized for the wire size.

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PA 14; 2012
Cape Fear River - NC

I had the same problem only on the right side. Turned out to be a fuse.

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2015 Hobie Tandem Island Hibiscus
"Third Normal Form"

• Trampolines
• Hobie cover
• Davis Spar Fly
• Kayakbob's Sprayskirts
• Spine Board Hakas