Umbilical and 7 Pin adaptor issues

[LowellN]

When I picked up my "new to me" AS the PO had wired the pigtail with the newer "common" plug (7 pin plug with the flat connectors in the round Plug). What he didn't know was that the "old" 7 pin plug with the round connectors isn't wired the same as the "new plug". So when I plugged the AS into my Pick-up funny things happened. With the truck turned off I plugged the AS into the truck. As soon as I did that the truck running lights came on, as well as the back up lights. I rewired the plug to what I think is the right format, but can't get all of the componets to work. I currently have only turn signals, brake lights, and back-up lights. I don't have running lights, running tail lights, electric brakes, or the acc. power. I have looked at the trailer service guide and it shows that after the wires come off the pigtial they have a fuse (box???) in them. 15 amp I think. I cannot locate these fuses (box???). Any help would be greatly appreciated, I'm started to get frustrated and don't want to have to spend the $$$ to take it to the garage to find the problem. Goodness knows that I need the $$$ for all the other repairs that the trailer needs.

Thanks,
Lowell

[overlander64]

Greetings Lowell!

Welcome to the world of Vintage Airstreaming!

What you describe is a common experience as Airstream used its own wiring schematic for the Bargman connectors durign the Vintage years. Both of my Vintage coaches required rewiring to the modern standard as utilized on my tow vehicles. The link below will take you to the wiring schematic that was originally used on the 1975 Airstreams:

1966-1981 Bargman Connector Wiring Schematic

I found it helpful to note the color/fuction relationship of each wire as they are not the same as the relationships that are currently used. The current wiring schematic that is nearly universally accepted can be found at:

Bargman Connector Wiring Schematic - - Current Industry Standard

To aid in resolving the issues before connecting to the tow vehicle, I utilized a 12-volt garden tractor battery with a set of heavy duty alligator clips to test each of the wires in the trailer's umbilical cord bundle to verify that it performed the function noted in the Airstream diagram - - in my case, the umbilical wires matched the functions described in the Airstream wiring diagrams.

If you still have difficulty after verifying that both your tow vehicle and coach have the same wiring schematic for the plugs, there are other places that you can check. The following are some typical observations:

1.) Clearance marker lights on the Vintage coaches can be temperamental. It is typically a ground. Repair often involves removing each individual marker light, cleaning the mounting surfaces and terminals, resealing/reinstalling.

2.) If turns signals/brake lights are an issue, the first course is to check the bulbs and cleanliness of contacts - - if corroded, clean contacts and replace bulbs if necessary. If the lights are still a problem, a reported source of difficulty is the junction box for the umbilical cord wiring (usually located just behind the curbside hitch "A"-frame in the bellypan - - it is usually covered by a square or rectangular panel held by either rivets of screws) - - cleaning the splices and re-weatherproofing is the usual repair.

3.) If the electric trailer brakes are an issue (do not operate), there are several potential issues. If the coach has been stored where it may have been exposed to overgrow weeds, it may have one or more wires in the brake system that have been broken. I know that this can become an issue from as little as 90-days parked in a field with wild ivys that twined themselves around the brake wires and snapped a couple when the trailer was pulled out of its storage area. Another potential problem is that if the breakaway cable were pulled and left detached for any length of time, the brake magnets may be been burned-out causing inoperable brakes.

Good luck with your troubleshooting!

Kevin

[LowellN]

Kevin,

Thanks for all of the info, I will definately be researching some of these issues. I have found some new information on the problem. I went to a local trailer supplier and was asking them their opinion on the problem when the service manager asked if I had the truck with me. I told him I did. He brought out a tester and tested the output at the connection at the rear of the truck. No reading for tail/clearance lights, or 12 volt acc.. It was all working the last time I towed my 1996 Sunline (2 weeks before buying the AS). I'm assuming that when I plugged the AS into the truck with the botched wiring job by the PO it blew something. The tow vehicle is a 2001 Dodge Ram 2500 Cummins Diesel. I looked under the hood in the fuse block and there is one 40 amp fuse that is marked "trailer", it's good. There is also a relay there, could this be bad? What would cause one thing to work and not another. I have also searched for the fuses for the "trailer lighting/brakes functions" but could not find them. I have the service book and it shows them, but I can't find them. Is this what is located under the front underbelly? I know the clearance lights work because they were working when they wern't supposed to (PO's awesome wiring job). Thanks again for all the help.

Lowell

[Inland RV Center, In]

Seven or nine pin round terminals = aircraft type plated terminals = peace of mind = no cleaning necessary = doesn't corrode = works every time.

Six or seven pin flat terminals = cheap connector = cheap unplated terminals = lots of gray hair = carry WD-40, small wire brush and beer, (to help with the patience) = works when it wants to, sometimes, as one grain of sand will open a circuit = always corrodes.

Andy

[john hd]

Seven or nine pin round terminals = aircraft type plated terminals = peace of mind = no cleaning necessary = doesn't corrode = works every time.

good point andy!

on the flipside, i like the flat 7 pin connector. if sprayed with lps 2 or an equivilent they seem to be mostly trouble free.

the thing i like about the seven pin connector wired to the general motors standard is that every one and their brother has one now!

if a person breaks down, the chances of the "rescue" vehicle being wired the same are pretty good. in my circle of family and friends i can think of eight vehicles that would be just a phone call away with exactly the same wiring as my silverado. (and yes i would supply the beer! )

a little piece of mind in exchange for a minor inconvienance of a lesser connector.

john

[Inland RV Center, In]

john hd

On the flip flip side, having a connector that everyone else has, makes it that much easier, for someone to very easily, hook up, plug in, and away they go with your trailer..............

Having a superior connector, that is not that common, adds a problem for someone that wants to steal your trailer.

If and when they tow it, with no lights, brakes, etc, some cop may see that, and pull them over.

Should someone have a breakdown, not a problem. That's what AAA is for.

So far, the advantages of the round terminals, far out weighs the flat terminals, without exception.

Andy

[markdoane]

Originally Posted by Inland RV Center, In

Should someone have a breakdown, not a problem. That's what AAA is for.
Andy

We don't all want to depend on AAA or Good Sams. I wouldn't use a round terminal connector unless I also carried a flat-to-round adapter. Just for the issues John mentions.

[LowellN]

I finally had time to dig in and find the problem. I'm not sure that one thing solved the problem, but most likely a combination of several things. I rewired the plug AGAIN. Cleaned all of the terminals. Put electrical grease on them. Located the interior access panel to the trailer end of the pigtail, and removed the connections and cleaned them. The ground was quite corroded so I think this was probably the bigest issue. Cut out and spliced a wire with a small amount of bare wire showing, and then hook it all back up. Bingo. Everything works, with the exception of a half dozen bulbs. I plan to replace most, if not all, of the clearance lamps. They are quite brittle from age. I'm certainly glad to have one thing checked off of the list.

Lowell

[Tarheel]

I love the idea of the battery but in my 74 the sockets themselfs were in bad shape. I ended up having to do a continuity check with each wire. It was a several hour affair, by myself, but it got the job done. WD-40 is a good lube and protector just don't pick up the clear lacquer by mistake like I did.

[A-Merry-Can]

once again.... THANKS AIRSTREAM FORUMS!!! i'm heading out to NC tomorrow with a new umbilical, AND brakes!!!

NEW CORD (yellow) --> TRAILER (black) : aux/back up
NEW CORD (black) --> TRAILER (blue) : charge line
NEW CORD (blue) --> TRAILER (yellow) : brake

off with brakes! i love it!

jp

[Ultradog]

at the flip up cover on the female side of the connector (the side on your TV) you will see a wiring diagram printed right into the plastic. I had to get down on my knees and put my reading glasses on to see it but it helped a lot getting things sorted out when I discovered it.

[uwe]

The round 7-pin is definitely superior to the flat7-pin. I speak from experience.
The flat is 20A rated, where the round is 30A, sometimes 35A rated. That's a 33% increase in amperage.
For those the have 12V fridges and electric/hydraulic brakes, the 7-pin round is a must have.
It is still a good idea to carry an adapter from 7-pin flat to 7-pin round, in case someone with a standard connector ( which sadly is a 7-pin flat) needs to rescue you.

[wkerfoot]

Originally Posted by uwe

The round 7-pin is definitely superior to the flat7-pin. I speak from experience.
The flat is 20A rated, where the round is 30A, sometimes 35A rated. That's a 33% increase in amperage.
For those the have 12V fridges and electric/hydraulic brakes, the 7-pin round is a must have.
It is still a good idea to carry an adapter from 7-pin flat to 7-pin round, in case someone with a standard connector ( which sadly is a 7-pin flat) needs to rescue you.

Interesting enough, the Airstream store at the International was selling the round pin connectors, but I did not see any flat pin connectors.

Bill

[ALANSD]

my new to me f 250 has the 7 pin blade type connector, my new to me 78 AS has the bigger round connector....can't seem to find the pieces to make an umbilical yet, tried etrailer, Grainger, Northern Tool and other sites....and ideas?

[uwe]

Originally Posted by ALANSD

my new to me f 250 has the 7 pin blade type connector, my new to me 78 AS has the bigger round connector....can't seem to find the pieces to make an umbilical yet, tried etrailer, Grainger, Northern Tool and other sites....and ideas?

Yes..
Buy a length of trailer cord, it's usually a mix of gauges and appropriate colors.
then get a 7-pin round for the trailer end, and a 7-pin flat for the car end, and use the Airstream wiring code on the round end, and the RV standard code on the flat end.
The Airstream code is on their website, the flat end's code is on the box the connector comes in, usually.

[ALANSD]

you mean change out the airstream end to the smaller modern plug style? The Soveriegn has the plug on the trailer to the left of the tongue, what happens to this covered plug...I am replacing the inside?
I did replace the flat on my 280 to a round..

[uwe]

Originally Posted by ALANSD

you mean change out the airstream end to the smaller modern plug style? The Soveriegn has the plug on the trailer to the left of the tongue, what happens to this covered plug...I am replacing the inside?
I did replace the flat on my 280 to a round..

Nonono, leave the Airstream end intact, and leave the car end intact, just buy 2 different plugs, and connect the wires to the corresponding pins.
You can alos change the car end to a 7-round ( which is electrically superior), but then it won't for any other modern trailer plug.

[ALANSD]

ok sorry to be thick, but where the heck do I find the end to fit the airstream plug? That is the one I can't seem to locate. I can get a blade or round for the truck no problem...

[uwe]

Originally Posted by ALANSD

ok sorry to be thick, but where the heck do I find the end to fit the airstream plug? That is the one I can't seem to locate. I can get a blade or round for the truck no problem...

OK, hang on....
Here we go:
Connector:
http://order.waytekwire.com/CGI-BIN/...D4A072+M37+ENG
or, try # 37675
For the cord, try : WT 702

Actually, you might want to simply order their catalog. You will need wiring supplies, and theirs are good stuff.

[wahoonc]

Alan,
Champion Trailers has everything you will need. Also look for a heavy truck store like Fleet Pride or possibly NAPA.

Aaron