I recently noticed the light on my brake controller flickering as I was cruising down the highway with the trailer behind me (this light is the one that lets you know you have a positive connection to the trailer). Anyhow, I pulled over and checked the plug, and it seemed a bit loose and I could actually wiggle it up and down and watch the trailer lights flicker... I checked all the pins when I got home, and they are all seated firmly and have the proper voltage at the right time. It just seems the female socket on the truck is no longer holding tight? Anyone else had this problem and what did you do to fix it, short of replacing the socket?

 

First thing I would check is the ground. Make sure a ground wire runs through the plug and has a good, clean, paint-free, connection on both sides. Take both sides off and clean them with a dremel or wire brush and re-install them. Next, hit them with a touch of spray paint or paint from a brush. Seal out the air and make sure they don't corrode.

Second, let's discuss how the 7-way RV style plug really sucks. Those flat blades don't work for crap. I hate mine. I pull trailers at least once, if not twice a week and I still have to put my plug in and wiggle before all connections work properly. Now, being an electrical engineer, that really tweaks me. If I did it all over again, I would buy the seven prong, metal, circular, plug like they use on semis. The reason I say this is becuase they make a cleaning brush for both ends, plug and receptacle. Shove the brush in both parts and remove, then connect. No problems! What a concept. These plastic RV style plugs are total crap!

Most times, if a trailer is flickering going down the road, it is because of the lack of a ground wire going through the plug. If you rely on the ball to ground the trailer, you'll get flicker more times than none. If you have the proper ground, you shouldn't have this.

1)Check the ground first, it is usally the culprit 75% of the time.
2)Clean the contacts on both plug and receptacle. You can use an ice pick and scrape, just don't scrape too hard and ruin the blades.(I'm assuming you have a RV style 7-way plug)

Hope this helps. I've had enough of these crappy connectors. I think I'll scroung up some circular mil connectors here at work and put them on. That would also curb the notion for buddies who borrow my trailers!!!

Good luck.

<edit> When you check voltage on your receptacle, take the backshell off the plug and plug it in. Then check the voltage on the back side of the plug with a load on it (the load being the lights or brakes). If you measure the proper voltage at the recept with out the plug in it, you might not be doing any good. If you have a bad connection, you won't notice a voltage drop until you put the plug in and measure down stream. Now, even if you have a bad connection, you may also measure the proper voltage downstream until you apply a load. (the whole, contact resistance, voltage drop thing). So, plug your lights in and measure at the bulb or apply the brakes and have someone measure the brake voltage at the brakes or as close as you can. You can use a sharp probe to pierce the wire and then put a wrap of tape back on it. Hope this additional info helps.

 

A little dialectric grease on the plug helps to keep it in good shape as well. Also, when the trailer is not in use, make sure your plug isn't sitting out in the rain or laying on the ground in the dirt. I added a velcro to my trailer so I can zip it up and keep it high and dry. Saves a ton of issues.

 

I was thinking it might be a ground issue, but I'm an electrical idiot so I figured I'd start by fishing for help This problem now happens on both of my trailers, so I'm really suspecting something in the pickup recepticle, but I guess it could be as simple as dirtly prongs?? I have no idea where the factory trailer wiring is grounded, so I guess I'll have to start tracing some wires? As for the trailer ground, the toy hauler ground location is also a mystery as its all in a 7-wire cable that is only exposed at the tongue. But the flatbed has a ground strap, and I know exactly where that is... Anyhow, thanks for the tips, I'll start looking.

 

The big problem I have with the plastic bodied plugs/receptacles is the fact that if a wire heats up, the plastic melts and the contacts move. After that, they are shot. I had rats eat up some wires in my stock trailer and when I plugged it in, it didn't blow a fuse, but melted the plug. The short was so far back that the short didn't draw enough current to blow the fuse due to the small guage of the wire.

This brings up another issue....trailer manufacturers may be able to build great trailers but CAN'T WIRE ONE FOR (bad word). They are the biggest, no-wirin' fools I've ever seen. I bought a brand new 24 foot flatbed and the first thing I did was re-wire the whole thing. 18 gauge wire may carry enough current for the loads demanded by lights....BUT NOT AT 24 FEET! Voltage drop you fools! They skimp on wire everytime.

Any way, before I got on a tangent, your receptable WILL allow the plug to be wiggled, they are just that CRAPPY of a design. A new on won't be any different. I think if you clean it good and put a dab of grease on them, they'll work fine, at least until they sit outside for a month. If we designed junk like this around here, we'd all be out of a job.

Good luck...again.

 

I agree with the dielectric grease. I use it on all of my trailers and haven't had any problems with them at all. I have had friends with the same problem as you and the never used any grease on the plugs. When they started to use the grease the problems stopped and they were happy. Hope this helps. As far as the electrical engineer goes some of what you say is true but the plugs that semis use will also have problems if not well maintained.

 

If you've got a plug melting, you need to check to make sure you have the proper wire size for what the circuit is pulling, test this with a meter, AND good connections. A properly sized conductor with good connections won't get hot and melt.