Trailer Brakes on a flat four plug

[Cam A]

Is it possible to run trailer brakes with only a flat four plug? I have no experience with trailer brakes. Could someone in the know give a brief trailer plug tutorial? Thanks

[Lee Hillsgrove]

The quick answer is no, you can't. All 4 leads are used for the minimum number of lighting functions, plus a ground. You have running lights, right stop and turn, left stop and turn, and the ground and that adds up to four.
Trailer brakes could very well require larger gauge wires then what would be incuded with the standard flat-4 arrangement.
I suppose that you could have 2 plugs, the flat-4 and another type for just the trailer brakes, but the best way to do it would be to go with the higher-capacity plugs that are standard on RVs. I think mine uses a round 7-position connector.

[CD Smith]

Sorry to differ with you.

There is an electronic box that can be added to your vehicle wiring that combines the left trun, right turn, and stop to operate over three wires. Fourth is vehicle ground.

These are available anywhere TV hitches are installed.

Then there is an adapter that can be used to convert four wire connector + electric brakes wire to seven wire connector.

I ran my Casita 17' SD with a Cadillac Deville DHS tow vehicle for two yearts connected this way.

[Byron Kinnaman]

Sorry to differ with you.

There is an electronic box that can be added to your vehicle wiring that combines the left trun, right turn, and stop to operate over three wires. Fourth is vehicle ground.

Running and tail light???
I think you have this backwards. There's an "electronic box" that will allow you to connect to a vehicle that seperate turn signal lights to work with trailer combination brake/turn signal light.

1 wire left turn, 1 wire right turn, 1 wire running & tail lights, 1 wire ground. When the brakes are applied both left and right turn lines become active turnning on both left and right turn lights.

These are available anywhere TV hitches are installed.

Then there is an adapter that can be used to convert four wire connector + electric brakes wire to seven wire connector.

I ran my Casita 17' SD with a Cadillac Deville DHS tow vehicle for two yearts connected this way.

If my count is right that's five wires. The 3 wires for the lights, the ground wire, and a seperate brake wire.


Why not just put in a 7 wire connector, and connect the wires needed. If you don't need the charge wire and the auxilliary leave them unconnected.

[MyronL]

Hello, CD....

It happens I just bought a Cadillac deVille and will be using it as my new tow vehicle. It's a 1990 deVille. I pick it up in a couple days. My first Caddy ...but anyway I am green as grass on electric hook-ups. Will this be easy? Hope to also be connecting electric brakes to my Burro, if possible, and would much appreciate any guidelines or tips, or even firm "Do THIS - Don't Do THIS" advice. (My Burro is currently still a work-in-progress, has a 7-pin round connector on it right now but its brake wires have been cut and I have not yet gotten the wheels off to see what's going on in there yet.)

Also have a challenging hitch conversion ahead to deal with but that will be a different thread.

[Byron Kinnaman]

Hello, CD....

It happens I just bought a Cadillac deVille and will be using it as my new tow vehicle. It's a 1990 deVille. I pick it up in a couple days. My first Caddy ...but anyway I am green as grass on electric hook-ups. Will this be easy? Hope to also be connecting electric brakes to my Burro, if possible, and would much appreciate any guidelines or tips, or even firm "Do THIS - Don't Do THIS" advice. (My Burro is currently still a work-in-progress, has a 7-pin round connector on it right now but its brake wires have been cut and I have not yet gotten the wheels off to see what's going on in there yet.)

Also have a challenging hitch conversion ahead to deal with but that will be a different thread.

Myron
I'm one of these guys that believes that some things are better left to people that know how. In the case of wiring in the brake controller and trailer connector I suggest that a local RV place might be what you want. If you mess up it's you and your trailer, if they mess up it their insurance rates.

I had the wiring done on my TV for the mess up reason above and I don't like messing around under a car. Hate dirt in my eyes. Oh! and I do know about electrons traveling in a piece of copper, so I could have done it.

[Roger H]

I'm with Byron. I've wired a number of trailer/brake controller/tow vehicle combos over the years, and I have had the last two done for me. It's just so much easier to let someone who does it on a daily basis take care of it. I don't have to re-learn it every time that way!

BTW, I've never seen an all-in-one box that converts European-style turn signals to U.S. standard AND has a brake controller built in. There were some trailer-mounted brake controllers out there for a while, but I've never seen one in person, and they don't allow the driver any manual control over the trailer brakes.

But, for the do-it-yourself type, it isn't difficult to do; just time consuming. You want to make sure that your "hot" and brake wires are properly breakered. Don't use butt-splices or you'll be re-wiring them on a regular basis. Solder or use appropriate weather-tight splices. You want to make sure that the wiring is of proper guage to handle the current that they need to handle, and then you need to figure out how to get them through the firewall without screwing anything else up, or causing them to chafe.

The actual wiring of the connectors is relatively easy, and there are a number of "cheat sheets" available on-line with the current "industry standard" wiring scheme. It's not rocket science, it just takes time and patience to do it right.

Roger

[Frederick L. Simson]

Is it possible to run trailer brakes [b]with only a flat four plug? I have no experience with trailer brakes. Could someone in the know give a brief trailer plug tutorial? Thanks

Flat 4? No. However, what I see a lot now here in California is a [b]Flat Five Plug and socket. Same as a Flat 4, but with the added blue wire for the electric brake controller.

white = ground
brown = tail; or running lights
green = right turn & brake
yellow = left turn & brake
blue = electric brake output from controller.

[Brian B-P]

Cam: I agree with Lee, Bryon, and Frederick - a four-pin connector will handle only the lights (assuming a combined stop/turn system), and not brakes. Everyone has listed those 4 wires consistently, and I believe correctly.

To add brake and battery charge functions, most suppliers of towing equipment have an adapter which is a 7-way socket with a 4-pin plug wired to it: you mount the adapter, plug it into an existing 4-pin trailer light socket for the light signals, and connect the ground wire and as many as you need of the three extras (blue for brake, black for battery charge, and yellow for any auxiliary function) to wiring which you must add (or have added) to the tow vehicle. This may be the adapter to which CD was referring. I use one between my Sienna (dealer-installed 4-pin light connector plus my own brake and charge wiring) and my Boler 1700 (original factory style of connection using 7-way RV connector).

CD and Lee: From my reading, you are saying the same thing - with combined brake/turn signals, the lights are a four-wire system.

Myron: if the Burro has a seven-pin round-bodied connector with a round centre pin surrounded by flat pins, you have the current RV standard: I believe that it is best to stay with this, even if some functions are not currently required. A tow vehicle set up with the full-blown system can always be adapted down to a trailer with lesser equipment, but not the other way around. This is what Bryon was suggesting.

Frederick: I can see how the flat-5 does everything some people need, but of course it precludes battery charging (or just running your refrigerator from the tow vehicle power in transit, even if the trailer battery doesn't get charged much). More importantly, the "bullet" contacts in the those in-line connectors are junk compared to the blades of the "Bargman" or "RV" 7-way connector. I have seen the 5-pin and 6-pin bullet connector blocks mostly as internal connections on the trailer (that stay plugged in until the umbillical cable to the tug is replaced), rather than the final trailer-to-tug connection that gets connected each time the trailer is hooked up.

[CD Smith]

Yes! There are only 5 wires required to operate lights and brakes on a Casita.

When I purchased my 2001 Deville I had a hitch and 4-wire connection added for my boat trailer. It consisted of an electronic box that combines some of the signals from the rear light assenblies to unloaded the circuits in the TV so the turn signal timimg was not affected and the ECM would not generate 'Check Engine' light indications.

When I purchased the Casita I also purchased a 4-wire to 7-wire adapter that also had a No. 10 Blue wire that was spliced to the No. 10 Blue wire from the Dexter Predator DX-2 Electric Brake Controler.

Only 5 wires to control running lights, tag light, brake lights, left turn light, right turn light, and brakes.

It really did work. A grand total of 11,456 miles.

Then I bought an Escalade and didn't have to worry about that anymore. Just splice the brake controller to the adapter cable and plug it in. The Escalade even had the holes drilled for mounting the brake controller. Plug in the Casita and 'Voila' it worked.

[Joe MacDonald]

I just have to jump in here, the flat four is definitely left,right, parks, and a ground.
the flat five is fast becoming popular for people who tow whopping big boats, that have brakes on the boat trailer.
there is also a round six pin ( not too common any more)
and a round four pin, (also not too common)
and of course the seven pin in two flavours, rv and transport ( blade and round pin respectively)

there are numerous boxes and converters, for european style orange signals, red brake lights to our North American standard.
there are now a lot of converters for newer North American vehicles that require their own feed and will take the load off your factory light circuit ( these may be required because the factories use very light-gauge wiring now, and it might not handle the extra load of the trailers lights) .

and who knows how many combinations of wiring adapters, 4-7 7-4, 6-4, 7-4 , 7-5 etc.

if you're not sure, get an expert, and save a lot of future headaches.

[Pete Dumbleton]

Here are pics and wiring info for Flat 4, Round 4, Flat 5, Round 5, Square 6, Round 6, and Bargman/Pollack 7; all have round pins except the B/P-7, which has 6 flat pins and one large round one:

http://www.etrailer.com/faq/wiring.asp

Pictures worth many words.

[Cam A]

Thanks, everyone; got all of the information that I needed.

[Craig Nold]

My Tacoma came with a towing package that had a flat 4 connector. The kit below had everything needed to convert to a 7-pin Bargman while not making any changes to the flat 4.
http://www.etrailer.com/Merchant2/merchant...ategory_Code=BC

[Roger H]

I guess that the key in deciding what connector to use is that most RVs and most tow vehicles come factory equipped now with the 7 pin Bargman-style connectors. That sort of makes them the defacto RV standard. If you wire your trailer and your tow vehicle to that standard, then you'll be able to use any tow vehicle with that standard with your trailer and vice-versa.

The others may be OK, but you'll either need adapters or a re-wire for each trailer you tow that's different. The 7-pin Bargman standard is quickly and easily reduced to the four-wire flat or five wire flat if need be by adapters that are universally available at auto parts and department stores. It's not so easy to quickly add wires as necessary to bring it up to the Bargman 7-pin standard.

Roger

[Harold Dean]

Myron
I'm one of these guys that believes that some things are better left to people that know how. In the case of wiring in the brake controller and trailer connector I suggest that a local RV place might be what you want. If you mess up it's you and your trailer, if they mess up it their insurance rates.

I had the wiring done on my TV for the mess up reason above and I don't like messing around under a car. Hate dirt in my eyes. Oh! and I do know about electrons traveling in a piece of copper, so I could have done it.

I guess I am going to have to ring in here with my two cents worth and side with Byron. I am a retired engineer and the later years were involved with sorting things out that were misdone. I adopted a motto years ago to cover this situation and it is "If you don't know what you are doing, don't do it". I have always advised younger engineers, that we old timers are not smarter than they, just more experienced and have made more mistakes and corrected them, so we pretty well know what won't work. We can keep you from going down that dead end and together we can explore the things that might work. Harold

[Benny K]

Good time to throw in this tidbit taken from the tyndall stone facade of a high school I went to........."Knowledge without practise makes but half an artist".......something that I`ll never forget.....Benny

[Gina D.]

I too know about them there electrons, BUT, I had someone else do my car/brake controller/charge wiring.

I know enough to know that if even the basics and theories are the same, it's the minor detail that will ruin your day every time. Since I am no specific exoert in auto electric, I let a pro do it.

Besides, it got done faster and it was WAY cheaper than MY hourly rate. I drove away with clean hands and a properly installed system.

[Frederick L. Simson]

Besides, it got done faster and it was WAY cheaper than MY hourly rate.

Yep. I can't afford Me, either.

[Per Walthinsen]

As a semi-retiree I CAN afford me, and if I do it myself I'll hopefully learn enough to repair it, modify it, and add to it without too much grief. That said, I regret that this country adopted the 110v system and not the 220v. With the higher voltage there is much more exitement when things go wrong, and my wife knows that I LIVE for exitement.