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4-Pin Trailer Plug Replacement

07/26/2016 11:48 AM

My SO got a new (to her) SUV last week. It's a Ford Escape and is in good shape, but the 4 pin vehicle-end trailer plug is quite corroded because the previous owner never capped or hid the plug from the elements. See the picture.

I'm trying to figure out the easiest/quickest/cheapest way to DIY this.

Cleaning

Try to clean the corrosion with a solvent and toothbrush, wire brush, etc. Plug is pretty corroded, so it may not work even after cleaning.

Replacement

  1. I can buy a replacement plug like this one. Directions seem too good to be true (cut plug, open new plug, insert wires, close new plug). The LEDs are a nice touch to ensure the connection is good.
  2. I can buy a plug extension, cut off the vehicle-end with the wires. Then strip, splice and solder new plug and wires to old wiring. Then tape and heat shrink tube for protection.

Novice questions alert

  • Which solvent would you recommend?
  • I'm assuming I need to depower the taillight/towing circuit before I begin this, right?
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#1

Re: 4-Pin Trailer Plug Replacement

07/26/2016 11:59 AM

I would suggest the new plug "like this one" be sure to disconnect your battery just to be safe.

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#2

Re: 4-Pin Trailer Plug Replacement

07/26/2016 12:45 PM

Go to a local automotive store, "O'Reilly's, NAPA, AutoZone" They should have some sort of a kit for replacing it.

We had a horse Trailer and my dad (us boys) was always fixing the faults... it was a pain in the butt, wiring was old and cracked. I was about 18 years old, and came across a complete wiring harness, and replaced it in the same amount of time it took to trouble shoot the faults. Worked great for years after.... Back, up hook up, check lights/turn signals/Brakes and go. Never had an issue.

I also recently bought a tester to test our truck trailer light connection works great.

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#3

Re: 4-Pin Trailer Plug Replacement

07/26/2016 12:50 PM

What! Gotham City has not auto parts stores?

"Salt and corrosion. The infamous old enemies of the crime fighter"

"Holy Homework" Hush try an auto parts store. Usually have a section with the many different plugs. And a repair harness that you are looking for.

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#4

Re: 4-Pin Trailer Plug Replacement

07/26/2016 1:20 PM

Not worth it to try to clean the corrosion products off of the old connector. The connector has lost most if not all of the protective plating so the result will be a connector that corrodes even faster.

However, if you decide to clean the existing one, I would recommend some acetic acid (vinegar) with a brass or stainless brush (or toothbrush, but ask your SO first), followed by thorough water rinse with a little sodium bicarbonate (baking soda) mixed in to neutralize any residual acid. Then a clean water rinse followed by spritz of isopropyl alcohol to dry out the water. Then apply an appropriate dielectric grease to help prevent further corrosion.

As for de-powering the circuits, the lawyers will tell you to disconnect the negative battery lead so your car will have "re-learn" all the transmission shift points all over again, and you will have to re-program all your favorite radio stations and mirror and seat memory settings, etc. The reality is that as long as the vehicle is off and no one is playing with the buttons on the dash, you are fine.

As for insulation displacement connectors like Scotchlok™, I avoid those unless you are at the side of the road and need a quick fix to keep you going. I'm old school. I prefer to cut off the old connector, strip back the wires (you may find that corrosion has 'wicked' its way a fairly long distance back into the wiring harness, if the copper strands are not bright and shiny, keep stripping), and then place adhesive lined shrink tubing over the wires (first ), then solder the wires, then use a heat gun to shrink the tubing down over the solder splices. You should see the clear adhesive ooze out of the ends of the shrink tubing just a little bit and that tells you the adhesive has flowed and created a watertight seal.

Get the heatshrink with the adhesive in it. China Freight sells a nice little kit for about $5 or $6 maybe less if on sale, with an assortment of sizes. They call it Marine Heat Shrink Tubing Assortment.

Or you could get some M23053/4-102-0.

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#6
In reply to #4

Re: 4-Pin Trailer Plug Replacement

07/26/2016 1:43 PM

Never knew about the Marine heat shrink. Thanks!

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#18
In reply to #6

Re: 4-Pin Trailer Plug Replacement

07/28/2016 7:15 PM

I've learned an awful lot by watching and talking with the technicians here at my work. Before I start any serious design work, I walk down to the shop and find out how those guys (and gals) will build it. Before I do any (official) design reviews, I take my concepts down to the shop floor and ask them first. They appreciate having input on the designs and material selections. They then have 'ownership' in the product and when the design goes to production they have my back. They're great people and there is no way I could repay them for the help they've given me over the years.

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#19
In reply to #18

Re: 4-Pin Trailer Plug Replacement

07/28/2016 8:19 PM

Good on you!

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#9
In reply to #4

Re: 4-Pin Trailer Plug Replacement

07/26/2016 3:11 PM

Thanks for your answer. I appreciate the thoroughness. I don't think I'll both trying to clean it. A trip to Tractor Supply is already called for, so I'll look for comparable shrink tubing. And good to know about disconnecting battery--I won't be running the radio while I do it then!

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#5

Re: 4-Pin Trailer Plug Replacement

07/26/2016 1:27 PM

IMHO: Your option 2 is the better choice. The replacement crimps in option1 (and others mentioned) will just move the corrosion spot from the plug to the crimp spot in the future.

Brave Sir Robin 's suggestion about the Marine heat shrink is a good one. I had never of that product until his post (time to go shopping!).

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#7

Re: 4-Pin Trailer Plug Replacement

07/26/2016 2:00 PM

Don't even bother trying to clean the old plug.

Cut the harness back until you have clean copper and install the new connector.

Squeeze the connector full of silicone rubber before installing it on the cable.

You'll very likely need one of these, too.

Adapter 7 Pole to 5 Pole Flat ... $10.95 etrailer.com Adapter 7 Pole to 5 Pole Flat Molded A-75TB $10.95 etrailer.com No tax

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#8
In reply to #7

Re: 4-Pin Trailer Plug Replacement

07/26/2016 2:51 PM

Yea those are always handy for when you want to pull a Class 4 or 5 trailer with your Class 1 or 2 vehicle and the wiring doesn't match.

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#11
In reply to #8

Re: 4-Pin Trailer Plug Replacement

07/26/2016 6:41 PM

The next time you go to town, take a look at the factory trailer connector on a Ford Escape. They aren't square any more.

You will find that the adaptor I showed is needed to hook a SQUARE FOUR PLUG trailer harness, like the one showed in HUSH's post to the newer Escort.

The class of trailer and vehicle is immaterial!

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#10
In reply to #7

Re: 4-Pin Trailer Plug Replacement

07/26/2016 3:12 PM

Good advice lyn, thanks!

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#12

Re: 4-Pin Trailer Plug Replacement

07/27/2016 1:47 AM

Honestly, I won't pull a trailer of any size with a Ford Escape, except maybe one of those from China Freight. But, towing a Ford Escape is probably a better option.

Either way, don't waste your time cleaning the old connector- replace it. Before next winter and done towing, pack the connector with some good cosmoline non corrosive/non conductive grease.

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#14
In reply to #12

Re: 4-Pin Trailer Plug Replacement

07/27/2016 7:29 AM

But, towing a Ford Escape is probably a better option.

Are you sure that not a Chevrolet Cavalier your towing?

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#15
In reply to #14

Re: 4-Pin Trailer Plug Replacement

07/27/2016 1:00 PM

"Are you sure that not a Chevrolet Cavalier your towing?"

You'd be considered a glutton for punishment, dragging your bad luck around with you

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#16
In reply to #15

Re: 4-Pin Trailer Plug Replacement

07/27/2016 1:05 PM

dragging your bad luck around with you

At least I have luck if it weren't for bad luck, I have no luck at all.

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#17
In reply to #16

Re: 4-Pin Trailer Plug Replacement

07/27/2016 9:34 PM

Yup, that is too funny

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#13

Re: 4-Pin Trailer Plug Replacement

07/27/2016 3:23 AM

I might clean something if I am on holiday when problems are found, but at home, it needs replacement.

I use WD-40 regularly, several times a year to prevent corrosion on my trailer connectors. I am told that Caramba is good too......you are fully correct to criticise the previous owner. But its a good reason to knock the price down!!

On thinking further along, if it was my job to fix, I think that I would cut the original cable at some point where the internal copper of the wire is still clean and uncorroded.

Pull it back inside the vehicle, coiling any "over-length" down somewhere inside the vehicle neatly, where no moisture will ever get to it, but you can!

A thick quality plastic bag may assist further here....or two!!

Fit a new connector at that point. Then make up an extension cable to the outside position, with a plug at one end and a socket on the other.

Then its always easy to repair if ever needed, or simply to remove and clean the extension, without getting underneath quite so much!!

Do use plenty of tie-wraps to make sure that no part of the cable can "swing-about" when driving...

I might even add some heavy duty inline fuses at that point as well, to make sure that cable damage, does not damage the car wiring....a 12 volt LED (one with a builtin resistor, possibly even one that flashes when activated!) mounted across each fuse, will alert the driver to a fuse being blown. Maybe mount the LEDs themselves where they can be easily seen?

Properly done and kept occasionally clean and protected with WD-40 or similar, it will probably never be needed to be redone, but a good selling point when that day comes....Professional!

Hopefully, a few useful ideas for you.....Pick out what you like!!!

PS. You would hate the job over here, the connector for Germany has 13 pins.

The UK still use the old 7 pin trailer connector that was Europe wide at one time, but add a "reverse" pinned 7 pin connector, for all the special bits that a caravan needs, but a trailer for cargo doesn't.

I am of the opinion that the UK version is the best idea, less sensitive, stronger design, so I made an adapter cable years ago, from the German 13 pin to the UK 2 x 7 pin as I still buy my caravans in the UK, better designed, better built!!

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