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Breiz · 02-26-2008, 10:48 AM

We're going to look at a 1977 29' Ambassador this weekend and we're going with tow gear hoping to buy it. This would be our first camper outside of a pop up and our first AS. It's for sale at an RV dealer. They told us on the phone that AS used a weird 7 round plug and they don't know how you plug it into your car (currently have a 7 flat plug on our car).

Could someone here enlighten me? Do I have to rewire the AS plug to a modern 7 flat? Is there an adapter to go from an AS 7 round to a modern 7 flat? If so, where do I get it?

I need something to tow it home 2.5 hours this weekend (hopefully)

Advice, suggestions, etc all welcome! Thanks!

TwinkytheKid · 02-26-2008, 10:53 AM

Quote:

Originally Posted by Breiz

Could someone here enlighten me? Do I have to rewire the AS plug to a modern 7 flat? Is there an adapter to go from an AS 7 round to a modern 7 flat? If so, where do I get it?

I need something to tow it home 2.5 hours this weekend (hopefully)

Advice, suggestions, etc all welcome! Thanks!

You have to rewire the plug to the new flat 7 prong plug. It needs the wires changed from the old standard to the new standard, too.

Breiz · 02-26-2008, 11:51 AM

The dealer just emailed me a pic of the plug and now I'm really confused. It's just a plug with pins in it in the wall of the AS. There's no cable. What am I not understanding here?

wkerfoot · 02-26-2008, 11:51 AM

Quote:

Originally Posted by Breiz

We're going to look at a 1977 29' Ambassador this weekend and we're going with tow gear hoping to buy it. This would be our first camper outside of a pop up and our first AS. It's for sale at an RV dealer. They told us on the phone that AS used a weird 7 round plug and they don't know how you plug it into your car (currently have a 7 flat plug on our car).

Could someone here enlighten me? Do I have to rewire the AS plug to a modern 7 flat? Is there an adapter to go from an AS 7 round to a modern 7 flat? If so, where do I get it?

I need something to tow it home 2.5 hours this weekend (hopefully)

Advice, suggestions, etc all welcome! Thanks!

The round plug is not wierd, it was the standard in the 1970's. It is still used on 18 wheelers and can be purchased at truck stops. Since you have the flat plug on your tow vehicle, you can either change the tow vehicle or the trailer. You will need a wiring diagram of the old plug as it is different from the current standard.

There are some who believe that the round plug works better and does not fail from corrosion as easy as the flat type.

bill

wkerfoot · 02-26-2008, 11:56 AM

Quote:

Originally Posted by Breiz

The dealer just emailed me a pic of the plug and now I'm really confused. It's just a plug with pins in it in the wall of the AS. There's no cable. What am I not understanding here?

You need a cable with plugs on both ends, common in the boating world. Like this but with seven pin plugs on both ends: Trailer Parts Superstore - 4-Pin Coiled Nite-Glow Extension Harness #47045

Bill

Breiz · 02-26-2008, 12:28 PM

OK we're thinking if we buy an umbilical cord and put a 7 round on one end and a 7 flat on the other then we can use the cord as an adapter. Everyone agree this is a doable plan? If so, then I need to find out where I buy an umbilical cord and the plugs. Thoughts? Oh and I need it here in like 2 days

Thanks again, you guys are the best!

wkerfoot · 02-26-2008, 12:39 PM

Quote:

Originally Posted by Breiz

OK we're thinking if we buy an umbilical cord and put a 7 round on one end and a 7 flat on the other then we can use the cord as an adapter. Everyone agree this is a doable plan? If so, then I need to find out where I buy an umbilical cord and the plugs. Thoughts? Oh and I need it here in like 2 days

Thanks again, you guys are the best!

Yes, you can do that, it will make it more difficult for someone to "borrow" your trailer since the borrower will not have any trailer lights or brakes.

The cable is available at RV supply stores, such as Camping World as is the flat plug for the round plug you will need a truck stop or perhaps a well stocked auto parts house.

Bill

wkerfoot · 02-26-2008, 12:50 PM

This is what I was looking for earlier. Unfortunately, it come with the flat plug only: Jet Connex

Bill

Ganglin · 02-26-2008, 01:59 PM

Advance Auto Parts at Mission and Lincoln has 4 7 pin round plugs in stock. You'll need that and a cable with a 7 pin flat that you can get from an rv dealer - Advance may have those also. That cable will have bare wires on the other end to wire your round plug to.

mswartz · 02-26-2008, 02:08 PM

Breiz,

Be sure to follow the very important suggestion from Bill above, and CONFIRM the wiring of your existing trailer connection.

I use the 7-circuit, round-pin, round body Pollack connectors on my tow vehicle and my Bambi. I have found these more reliable and less prone to corrosion than the original 7-circuit flat-pin Bargman connectors. But the flat-pins have been used very successfully by millions, and, as all connectors, are generally quite reliable when maintained.

A good place to start is: How to Wire your Car or Truck for Trailer Lights, which shows a wide variety of connectors and provides suggestions on installation and testing.

Tekonsha has a page describing 7-conductor flat-pin connectors and wiring on the site: http://www.tekonsha.com/files/wiringdiag.jpg

One website with diagrams of 'standard' wiring of 'round-pin' round body trailer connectors can be found at: trailer_wiring_diagram.

Also see, for example, sites showing 7-circuit connector wiring diagrams for various tow vehicles; for example: Marksrv.com 7 way wiring diagram page .

It is also critical that you not assume that wire color-codes inside multi-conductor cables are standardized. Always use an ohmmeter to trace each wire to the associated pin of the connector.

When you can confirm the circuitry of your trailer connector, then you can decide to change connectors or make a custom cable.

Post any questions on the site and you'll have plenty of good suggestions.

Regards, Marshall

Breiz · 02-26-2008, 02:44 PM

OK new info:

The dealer just emailed me and said she does have the cable for the AS, however BOTH ends on the cable are 7 round male ends. Why would they both be male? Looking at the pic she sent me of the 7 round receptacle on the AS body, it looks male to me.

mswartz · 02-26-2008, 02:50 PM

Breitz,
I see you're in Latrobe. I grew up in Greensburg, where I got my Bambi.

Ten miles from your home you can contact Carl and Alex, who used to be at Turner Airstream (until it closed) and are now at Airstream of Western PA (Ranger Trailer) in Greensburg, near the old ITE transformer plant in Southwest. Give them a call at (724) 837-2753 to discuss your needs and they may have a suggestion.

Also, on the etrailer site you'll find: Adapter 7 Way (Blade) to 7 Way (Round Pin) 37595 : Trailer hitch bike rack and trailer hitches - etrailer.com

Good luck,
Marshall

Journalist · 02-26-2008, 02:58 PM

I use the old 7-round. My father's trailers all have them, so it made it easy for me if I needed to borrow one of his big utility trailers or the car hauler to have the plug already installed on the truck. I keep a supply of adapters in my truck toolbox for hitching up to other things, just in case.

mswartz · 02-26-2008, 03:03 PM

Also see this thread on the forum which discusses a special 7-circuit plug on a late-60's era Airstream:

http://www.airforums.com/forums/f37/...pin-17761.html

Motoman · 02-26-2008, 07:30 PM

I am confused by something that Breiz said at the beginning of this thread; hooking a old 7 pin connector to a modern "flat" 7 pin connector. I have not seen a 7 pin flat connector on any modern tow vehicle, Dodge, Ford, Chevy, Toyota, etc. The only flat connectors I am aware of are four pin for lights only; brake, running and turn signal but no electric brake control. Our Dodge has both connectors but the four pin is just for light utility trailers, the 7 pin is a "modern" connector for heavy trailers with brakes.

Did I miss something or is there another style connector

Area63 · 02-26-2008, 07:38 PM

Quote:

Originally Posted by Motoman

I am confused by something that Breiz said at the beginning of this thread; hooking a old 7 pin connector to a modern "flat" 7 pin connector. I have not seen a 7 pin flat connector on any modern tow vehicle, Dodge, Ford, Chevy, Toyota, etc. The only flat connectors I am aware of are four pin for lights only; brake, running and turn signal but no electric brake control. Our Dodge has both connectors but the four pin is just for light utility trailers, the 7 pin is a "modern" connector for heavy trailers with brakes.

Did I miss something or is there another style connector

Both connectors are round, but the one in question here has round pins inside a round plug. The commonly used, low amperage RV one has 7 flat pins inside the round plug.

empresley · 02-26-2008, 07:40 PM

Quote:

Originally Posted by Motoman

I am confused by something that Breiz said at the beginning of this thread; hooking a old 7 pin connector to a modern "flat" 7 pin connector. I have not seen a 7 pin flat connector on any modern tow vehicle, Dodge, Ford, Chevy, Toyota, etc. The only flat connectors I am aware of are four pin for lights only; brake, running and turn signal but no electric brake control. Our Dodge has both connectors but the four pin is just for light utility trailers, the 7 pin is a "modern" connector for heavy trailers with brakes.

Did I miss something or is there another style connector

The plug itself is round. The flat connectors are in reference to the actual contact points built into the plug. RV plugs have flat contact points. Commerical 7 pin plugs have round pins for connection.

Area63 · 02-26-2008, 07:41 PM

This should shed some light on things.
Airstream, Inc :: FAQ
The 7-round plug is indeed a better quality connection. If it were me, and if I did not have to pull other trailers, I would convert the truck end to a 7-pin round and make the umbilical cord with 2 of the same round plugs. They are self cleaning, and provide a better electrical connection than the flat terminal RV plugs. There is a reason the professional drivers use these in their 18 wheelers. I have used the 7-pin rounf metal truck end on both my Suburbans, and foud them to be a very positive and safe connection.
However, the standard is still the 7-pin flat.

Excella CM · 02-26-2008, 11:07 PM

Another point of confusion. The overall shape of the plug on the AS umbilical cord is round male, BUT, the actual connectors are female. The pins are in the TV and trailer, the sockets are in the umbilical.

Clear as mud, huh?

Breiz · 02-27-2008, 02:37 PM

Yes, my suburban connector is round in shape, I meant the pins were flat. So today I went to murray's auto Electric and bought an $8 connector that has one end where the umbilical will go in and another end that will plug into my 7 pin fla t on my Suburban. So the current plan is to use their umbilical, plug one end into the AS, hack off the other end and attempt to wire it to the newly purchased 7 pin flat connector. If that works, the I'llend up with an umbilical that has a 7 round on one end and a 7 flat on the other. Then, in theory we can plug into the Suburban and go (if only it is that simple). We're going to attempt this in the rv dealer's parking lot, did I mention that? Wish us luck!

The main problem I can see (aside from the ridiculous weather here in PA) is that we could wire it correctly only to not have any lights function. Then we'll be wondering did we wire it wrong or were the lights non-functioning already.