A Common Sense Lesson in… Trailer Wiring?

Yes, trailers, specifically trailer lights. Trailer lighting is not common sense to most people, but if you work with trailers a lot, it will be for you. So, let me describe my experience where i missed what others might consider to be “common sense”.

4 pin trailer light plug

Image courtesy of www.fishing-tips-bait-tackle.com

For the rest of this story to make sense, we need to establish a few basics as to who electrical systems work in cars. don’t’ worry, this is very high level stuff, so if that’s not your thing, just stick with me.

The biggest thing to keep in mind, when dealing with any DC power system is the ground. Everything has to ground back to the frame to complete a circuit. Well, the trailer is no different.


The trailer has it’s own ground. Everything grounds back to the frame, but when the power source is the tow vehicle, then they need to share a common ground. This part is actually simple. When you connect the hitch, the metal to metal contact connects the two frames together, and viola, you have a common ground.


Ok, so now that we have that out of the way, here is what happened to me. I came to require the need of a trailer hitch. My truck originally did not come with one, so we had one installed. Sounds simple enough, right? Especially when someone else does the install. That makes it far easier for me, at least at first.


Then, panic sets in when the first time you hook up to the trailer and the lights don’t work. I have pulled trailers many times over the years, but never had I hooked up to a brand new hitch, and had no idea what problems could arise.


So, what could possibly be wrong with an all new setup that was professionally installed? Well, remember that ground issue from earlier? The hitch is where a common ground is established between the tow vehicle and the trailer. With all brand new parts, parts that are painted, there is no direct metal to metal connection, hence no electrical connection can be established. The paint is enough to insulate that 12V current from making a ground between the two.


Sounds simple right? It is, when you finally figure out what’s going on. This is the perfect example of how common sense is developed through experience. Someone who has installed a lot of hitches would probably be familiar with this phenomenon. For me, who had actually never used a brand new hitch setup before, I was clueless.


As far as I knew, you slide the piece with the ball into the receiver, hook up to the trailer, and everything should work. Someone at a trailer company, or an RV dealer, might think something along the lines of, “Of course you need to be sure it’s grounded” but I took it for granted. I figured that hooking a metal hitch to a metal ball was sufficient. Only after searching Google and watching a couple YouTube videos did it dawn on me what was happening. After taking off the ball, 5 minutes with the angle grinder, and installing it all again, it all worked.


I know this is way off topic from the norm here, but it’s a great example of how what someone considers as “common sense” is something the next person would not even think of. Everyone thinks differently, and has had different experiences that have shaped their entire thought process. For example, look at your spouse or significant other. How often do you have an issue of them not understanding what you are trying to say? Have you stopped to think that maybe their thought structure is different from yours?


What seems one way to you might come across as completely different to the other person. Now, both of you can help this situation. One, you could try and frame conversations in a way that your significant other will better understand. As the other person, you could try to understand how that person thinks, and if you take offense to what they said, be sure of the intent before becoming angry. If you both try to work toward a better understanding of the other, any relationship can benefit from this.


How many times have you gotten a relationship lesson from trailer wiring? Yeah, it was a first for me too. Do you have an odd situation where you learned something that could apply to many other areas of life? If so, please share in the comment section below.

In the meantime, head over to Amazon and check out the Average Joe book series. I think you will enjoy them.