View Full Version : OT: Help needed. Problem w/ trailer connector.

Your Old Dog
06-27-2007, 03:41 PM
I have a pickup truck that I haul my travel trailer around with. Some ignorant fool, I prefer not to say who, thought he'd be doing a good turn if he filled up both the truck and trailers connectors up with "Dielectric Silicon Compound". After he saw the error of his ways he has made several attempts to remove said grease from the connectors. He has tried a power washer but that only removed the thick gobs but not all of the grease. When I, I mean he, tried putting some of the Dielectric on a plastic saucer and dilute it with alcohol, mineral spirits and acetone it didn't seem to phase the grease.

Any clue how I might clean this stuff off? If I have to I can replace the trucks connector, it's just expensive. The trailer on the other hand will require a lot of fooling around to correct. I need something to dissolve silicon?

I'll be taking it to some hilly areas and it'd sure be nice to have the breaks operational as the trailer is 7,000 pounds :D It's very reassuring when you tap the break and feel the trailer slowing down instead of pushing you.

Alistair Hosie
06-27-2007, 04:02 PM
HI YODA what is dielectric silicon and what problem is it causing exactly sorry to be so unknowledgable but I would like to know kindest regards Alistair

06-27-2007, 04:08 PM
Dielectric is stuff that acts like insulation, there are fluids that you can put a an electric motor in the liquid and it wont short it out.

My first guess would be hit it with a can of brake cleaner and see if that works. Or contact cleaner.

06-27-2007, 04:09 PM
YOD, the diaelectric grease is supposed to enhance the conductivity of connections. Allmost all mechinics use it on the plugs on cars and trucks for bad connectors everywhere. If your brakes are not working something is wrong with them, not the grease. I put a small dab on the male plugs and work it into the female plug. It does tend to collect dirt, etc. but I keep the plugs covered.

I did a google and the grease is not conductive but prevents moisture from entering. The grease allows the metal parts to make good contact and heat transfer in some cases. From what I read it should not cause a failure to make contact. Even manufacturers use the stuff.

You must have some other problem. Broken wire, bad connections somewhere else, bad brake controller, etc.

06-27-2007, 04:25 PM
Dielectric grease is appropriate. Don't remove it.

06-27-2007, 04:43 PM
Yeah, I normally put it in my boat trailer light sockets and connectors, was there a prior issue leading you to think water intrusion was a problem?

I agree, it sounds like the problem is elsewhere, unless it wasn't die-electric grease?


Your Old Dog
06-27-2007, 05:13 PM
Thanks everyone for your input. I put it on to retard the oxidation process but as soon as I used it I started having problems with the trailers electrics. Maybe I'll start by changing out the trucks connector and see where that leaves me as the connector on the trailer is brand new.

06-27-2007, 05:19 PM
Sounds like you may just have used TOO much. Borrow the wife's portable hair dryer, heat up the connectors, and sling out the excess!

06-27-2007, 08:17 PM
YOD, look at page 2, under cleanup.


06-27-2007, 08:45 PM
YOD , I have trouble with my trailer brakes and lights every spring too. My troubles are a poor or no ground caused by corrosion (rust) in the receiver hole , up inside the trailer hitch where the ball seats etc. During the towing season all the metal parts of the hitch and ball become very shiny then rust during the winter. I use a jumper ground wire between the truck and trailer for the first few miles , then all is OK for the rest of season. JIM

06-27-2007, 09:32 PM
Do you use the small round 6-pole connector?

If so, there is a storage device for it that I use on my small trailer, it's made by Cole-Hersee. The connector goes into it, when not being used.
I used to have problems with critters building nests of mud in mine, until I added one of these.

I haven't found one for my RV style connector yet, on my cargo trailer.

here is a link for the 7-Pole. There is another model on an adjoining page.

Your Old Dog
06-28-2007, 10:47 AM
This place still amazes me! :D

More good info. Looks like I'll try the mineral spirits as mentioned in the pdf file and then the hairdryer to melt/sling it out.

If all this is ridiing on the ground wire then I think I will also put in a seperate ground wire that I can trust. One that won't depend on the trailer ball for a contact.

06-28-2007, 12:07 PM
There is a lot of good advice in the replies


the ones that say that dielectric compound is a conductor.



A Dielectric compound is an INSULATOR.

You know this already as you have gone from poor performance to no performance.

I am posting this only to clarify conflicting earlier posts.

06-28-2007, 12:41 PM
The hair dryer might soften things up a bit, but notice in the pdf that the dielectric compound has a working temperature of 450 F!
Most trailer wiring connectors should have a separate ground terminal, if you are experiencing erratic electrical behavior I suspect a bad ground circuit first, easy to check by substituting a known good ground wire temporarily.
Below is a pin out of what I think you are working with.


06-28-2007, 03:27 PM
Jim, a proper connector includes a ground, performing the same function as your jumper.

06-28-2007, 09:55 PM
The hitch should never, ever be used for the ground connection, always use the proper conductor in the connector(s).

When I wired my truck, I used a Hoppy Lighting Isolator, a solid-state relay device that draws power from the battery through a circuit breaker and is triggered by the truck's lighting circuits. No appreciable power is handled by the truck's wiring. The Hoppy and other wires (brake controller and charge circuit) go through a 7-circuit junction box that's meant for this purpose; I got it from NAPA and believe that it's used on semi trailers. A 25' length of 7-conductor trailer light cable runs from the J-box all the way to the connector on the rear of the truck, no splices into the truck's wiring under the bed.

The trailer is wired similarly: the trailer's wiring umbilical goes through one of those J-boxes that's mounted on the hitch 'A' frame, then the connector and 6' umbilical cable is attached to the J-box. Makes it easy to replace the umbilical and connector if/when it becomes necessary.

The J-boxes make for a neat job, IMO, and make troubleshooting very simple. Pop the lid (it's pretty much weatherproof) and clip the ol' test light onto the binding posts.

This is for my travel trailer; my flat-bed utility trailer will get the same treatment when I overhaul it.

06-28-2007, 11:19 PM
Got news for you... I've been using it for years on my trailer plugs, nary a problem. Keeps water out and the electrons in. Your power to your lights or brakes, depend on a mechanical wiping and pressure action as they are plugged in to make the connection.

Someone else said what I was going to say... make sure your ground wire from the truck/car is heavy wire, good clean tight connection.
I'm almost of the opinion that after, say... 5 to 10 years depending on where you live and how much salt they use on the roads in the winter, its wise to just replace all the lights and connectors on a trailer.

06-28-2007, 11:25 PM
Chipmaker, and all others who corrected me on the ground, you are correct. I do truck repair for a living , know better , do better on the job, just not on my own JIM stuff. Yes there should be a good ground in the trailer electric cord!!

06-28-2007, 11:26 PM
Chipmaker, and all others who corrected me on the ground, you are correct. I do truck repair for a living , know better , do better on the job, just not on my own stuff. Yes there should be a good ground in the trailer electric cord!! JIM

Marc M
06-29-2007, 10:49 PM
I worked at a company that made wire guided material handling equipment. Due to condensation problems, any vehicles that were headed for service that involved freezers had a number of special parts and procedures applied. Amongst these were to completely fill all connector cavities with dielectric grease - you can't use 'too much'. The only functions of the grease is to prevent foreign contamination and oxidation. Normally there is enough spring pressure in the contacts to effectively scrape the grease away as it's inserted and maintain a solid connection. If your connection is now failing, it's possible the males are compressed and/or the females have spread. Incidentally, I also spent 15+ years in the truck/trailer repair business.