Wiring a Breakaway Switch

[jerryc41]

What is the proper procedure for wiring a little Bargeman breakaway switch into a 1973 31' Airstream? Let's assume that I do not currently have the correct wiring at the A-frame.

[Wingeezer]

I've never done it and certainly stand to be corrected, but I would think you would just need to bring a decent sized wire (maybe #14 or #12?) via an in-line fuse, from the plus side of your coach battery or batteries to one side of the switch, and then run from the other side of the switch to the brake feed wire on the trailer - once you identify which wire it is !

Are you saying that your trailer does not have a standard 7 pin connector?

If it does, there are lots of diagrams on line to show how it should be wired and which would be the feed wire to the brakes - I don't recall off hand.

Brian.

[idroba]

Three possible ways:

1. Find the 12 volt supply wire which will go to your umbilical cord socket. (I think the 73's still used a socket in the front with a two ended umbilical cord). Access to the back of the plug is inside, under a white plastic cover which may be buried below the couch or whatever is in the front of your floor plan. While you are there locate the wire which goes to the trailer brakes. Run a wire from each of those to the break away switch and you will be done.

2. Alternatively, since your trailer originally had a break away switch, see if you can locate the two original wires which went to it. One should have +12 volts on it, the other should activate the brakes when attached to 12 volts.

3. If you have an electric jack that works, the power to it can be your +12 volts, and all you need to do is to find the brake wire line for the other side of the break away switch.

[Inland RV Center, In]

Originally Posted by jerryc41

What is the proper procedure for wiring a little Bargeman breakaway switch into a 1973 31' Airstream? Let's assume that I do not currently have the correct wiring at the A-frame.

Breakaway switches are wired directly to 12 volts dc and then to the "HOT" wire of the brakes.Make sure you ID the hot side. If not, you will be hooked up to a ground.

If you pull the cable, that switch will burn up very quickly, "IF" the cold side is wired to the ground.

Andy.

[jerryc41]

Originally Posted by idroba

Three possible ways:

1. Find the 12 volt supply wire which will go to your umbilical cord socket. (I think the 73's still used a socket in the front with a two ended umbilical cord). Access to the back of the plug is inside, under a white plastic cover which may be buried below the couch or whatever is in the front of your floor plan. While you are there locate the wire which goes to the trailer brakes. Run a wire from each of those to the break away switch and you will be done.

2. Alternatively, since your trailer originally had a break away switch, see if you can locate the two original wires which went to it. One should have +12 volts on it, the other should activate the brakes when attached to 12 volts.

3. If you have an electric jack that works, the power to it can be your +12 volts, and all you need to do is to find the brake wire line for the other side of the break away switch.

Thanks. I have two wires emerging from the A-frame, but they both seem to be dead. I'm running a new wire for the jack, and I guess I'll have to do the same for the breakaway switch. Your info on the 7-way connector will help me find the brake wire, but - big question:

How can I get the wire form the 7-way plug inside the trailer to the breakaway switch at the end of the A-frame?

[Inland RV Center, In]

Originally Posted by jerryc41

Thanks. I have two wires emerging from the A-frame, but they both seem to be dead. I'm running a new wire for the jack, and I guess I'll have to do the same for the breakaway switch. Your info on the 7-way connector will help me find the brake wire, but - big question:

How can I get the wire form the 7-way plug inside the trailer to the breakaway switch at the end of the A-frame?

There is an inspection plate underneath the front end of the trailer.

Remove that plate, and you should find where the front cable connects to the rest of the wires.

Andy

[jerryc41]

Originally Posted by Inland RV Center, In

There is an inspection plate underneath the front end of the trailer.

Remove that plate, and you should find where the front cable connects to the rest of the wires.

Andy

Thanks. I'll take a look.

[jerryc41]

Originally Posted by jerryc41

Thanks. I'll take a look.

There is no inspection plate - just the smooth bottom of the trailer.

[idroba]

The inspection plates seem to be variable, I have had AS and Argosy trailers with them and without them. So, without it, you have no easy way to get up through the belly pan area and to the rear of the connection on the trailer shell. What I probably would do if I had your rig would be to cut a piece out of the belly pan to make your own inspection area, and cover it up when done with a larger metal patch, screwed in place over the hole you have cut. In other words, make your own inspection plate.

I can't think of any other easy way to do it.

[jerryc41]

Originally Posted by idroba

The inspection plates seem to be variable, I have had AS and Argosy trailers with them and without them. So, without it, you have no easy way to get up through the belly pan area and to the rear of the connection on the trailer shell. What I probably would do if I had your rig would be to cut a piece out of the belly pan to make your own inspection area, and cover it up when done with a larger metal patch, screwed in place over the hole you have cut. In other words, make your own inspection plate.

I can't think of any other easy way to do it.

Thanks. I'm trying to figure out which wire inside the connector is for the brakes. Diagrams for the 7-way usually show a blue wire for the brakes, but I have a green in that position. I got the jack working, so I'll tackle the B-A switch tomorrow.

[idroba]

From memory only now....on your year Airstream I think the brake wire is yellow, but don't hold your breath.

[jerryc41]

Originally Posted by idroba

From memory only now....on your year Airstream I think the brake wire is yellow, but don't hold your breath.

Yellow would make sense because one of the two wires coming out of the A-frame looks like it had been yellow at one time. The trouble is it looks like it had been chewed by mice here and there. I could tape the parts I see, but there might be more chewing that I can't see inside the frame.

I'll try to see if the faded yellow wire I have up front is going to the brake terminal in the 7-way. Then I can try to run a new wire from that terminal. I've looked up 7-way connectors online, and there are too many color combinations. Going back to 1973, there were probably no standards at all.

[rogerdodger]

On the old Airstreams, the brake switch is connected between the Blue wire, which is +12 trailer battery, and the Yellow wire, which is brakes. However, do not hook up this way until you have checked with a meter, as you will be applying +12 volts, which could burn up a lot of trailer wiring if some PO has re-wired things differently. When I re-wired my Argosy, I fused the Blue wire at the terminal near the battery. That way, if I made a mistake, I would blow a fuse before I took out internal wiring.
If the jack is working, that is a good point to connect the brake switch. Also, remember not to test the brake switch with the T.V. connected, as this could cause 12 Volts applied to your brake controller, which could burn it out.

[idroba]

If you suspect your brake wire, by all means replace it with a new one, perhaps run under the belly pan, well protected with some flex conduit. Those old brake wires are often suspect in any event, and corrosion works it's way up the insulation from the point the wire attaches to the magnets. I think you would be safest if you did it that way.

You will run two wires in the conduit, one is the hot, the other is the negative or wire attached to the white "ground" wire from the battery and tow vehicle. It does not matter which wire attaches to which on the brake magnet side. Use crimped connections, with heat shrink tubing for insulation where you splice it, and connect to the magnets.

[jerryc41]

Originally Posted by idroba

If you suspect your brake wire, by all means replace it with a new one, perhaps run under the belly pan, well protected with some flex conduit. Those old brake wires are often suspect in any event, and corrosion works it's way up the insulation from the point the wire attaches to the magnets. I think you would be safest if you did it that way.

You will run two wires in the conduit, one is the hot, the other is the negative or wire attached to the white "ground" wire from the battery and tow vehicle. It does not matter which wire attaches to which on the brake magnet side. Use crimped connections, with heat shrink tubing for insulation where you splice it, and connect to the magnets.

You've given me a new point of attack. I can look for the brake wire at the brakes themselves and run that wire forward. That way, I won't have to worry about what color Airstream decided to use on the day my trailer was built. I'm assuming the wire will be visible running into the brake drum. If the wire runs under the belly pan from one brake to the other, I'll run a new wire for both sides. Otherwise, I'll run a new wire from whichever side gives me access to the wire.

A few days ago, I ran a new wire from the battery to the jack. I enclosed it in clear vinyl tubing and attached it to the gas pipe with cable ties, so it's well-protected.

[jerryc41]

Originally Posted by idroba

If you suspect your brake wire, by all means replace it with a new one, perhaps run under the belly pan, well protected with some flex conduit. Those old brake wires are often suspect in any event, and corrosion works it's way up the insulation from the point the wire attaches to the magnets. I think you would be safest if you did it that way.

You will run two wires in the conduit, one is the hot, the other is the negative or wire attached to the white "ground" wire from the battery and tow vehicle. It does not matter which wire attaches to which on the brake magnet side. Use crimped connections, with heat shrink tubing for insulation where you splice it, and connect to the magnets.

I thought I had posted a follow-up question, but I don't see it. I decided to run a wire directly to the wheels from the A-frame/breakaway switch. There is a "Brake Cable" containing two wires near the wheels. One wire is black, and the other is gray(?). Red wires are connected to each and run to the wheels.

So, I run a hot wire to one of those wires that go to the brake - the black one? I tap into that hot wire with one of the wires from the B-A switch.

Then I connect the B-A switch to ground,

The result is that the brake has a hot wire connected to it, and the ground is completed when the pin on the B-W switch is pulled?

It's late, and my brain keeps cutting out.

[rogerdodger]

NoNo, don't do that. The Breakaway switch is supposed to send the battery 12 volts to the brakes to apply them in an emergency. Don't connect the switch to ground!!

[jerryc41]

Originally Posted by rogerdodger

NoNo, don't do that. The Breakaway switch is supposed to send the battery 12 volts to the brakes to apply them in an emergency. Don't connect the switch to ground!!

That's why I am patient - no burn-outs needed. So, one wire on the switch goes to hot, and the other one goes to the brakes. The question still remains: at the wheels, I have a black wire and a gray wire coming from the front of the trailer to the brakes. These are paired together with insulation labeled "Brake Wires." A red wire runs from each of them to the brakes. Where do I connect the wire coming from the B-A switch, to the black wire or to the gray?

[azflycaster]

The switched wire from the break away switch is normally connected to the brake connector in the seven pin cable from the TV. On my trailer the connector is on the front wall behind the gaucho.

[jerryc41]

Originally Posted by azflycaster

The switched wire from the break away switch is normally connected to the brake connector in the seven pin cable from the TV. On my trailer the connector is on the front wall behind the gaucho.

I found that, and the brake wire is probably yellow. The problem is getting the wire from the 7-way connector inside the trailer to the outside. I thought I could drill straight down, but there's too much frame in the way. Running it straight back under the trailer, enclosed in vinyl tubing, will be easier, but I have to know where to connect the B-A switch at the wheels.