Break-AWAY Power.

[raebaker06]

I have a 1974/5 22ft Argosy. I have an electric tongue hoist and have only 1.5 volts at the brake-away lead.
I need to know where does the power come from .
I have the service manual and it shows everything but the brakes and brake-away wiring.
I am moderately proficient in electronics , but I need information to become wonderful, and resolve my problem.

A detailed explaination would be most appreciated by this old Fart. My problem is I have pulmiary fibrosis and have extreemly limit Oxygen take up so I some times have trouble when using the facility. There is no one around here willing to help me. Guess Canadians are to far north and in the woods.

Your expert advice will make life a bit better.

Regards

Rae Baker
Burlington,Ontario
Canada
rbaker.1@netzero.com

[wasagachris]

Rae if you have full voltage at the battery then 1.5 volts at the break-away lead it is an indication of a bad or poor ground. It grounds out through the mounting point to the tongue. Try removing that bolt clean underneath it and clean the mouting point, reinstall and check it again. When you are checking the voltage make sure you have a clean point on the tongue to use. Scratch until you see bare metal.
BTW Burlington is not that far north or any where near the woods.

[Phoenix]

Just to make sure we are talking about the same thing: Is this the "break-away switch" with a lanyard that attaches to your tow vehicle, that activates the electric trailer brakes if and when the trailer separates from the tow vehicle?

If it is, the power comes from your 12 volt house batteries. I haven't looked at the wiring diagrams (and the wiring may differ between model years 1974 and 2005), but I think the source wire is attached to the +12v buss bar where most all 12v devices get their power. In our 2005, 19-foot Bambi, it's under the bench seat at the front dinette, near the fresh water tank, against the front wall of the trailer. I'm not sure where it would be on your Airstream.

Also, with no load applied, I would think that this wire should measure between 12 and 13 volts (the same as the positive terminal on the battery) versus chassis ground.

===========

Just had a thought, that switch should be open with the lanyard attached. One side should measure +12 volts, but the other may have some residual voltage returned from the electric brakes. I would think that it should measure "zero" volts, but you may have a some slight leakage from a poor or floating ground from the brakes.

[wasagachris]

Rae the break away switch is tied to the power line feeding the tongue jack. It in turn feeds from the mian charge line which comes from the battery/converter and from the TV when the umbilical is connected. The other wire coming out of the break away switch is connected to the brake wiring. Both wires from the switch are + DC. Phoenix is correct that if you are measuring across the switch, that on both wires with the pin still in the voltage should be 0 as the switch is open or off.
The tongue jack wiring and brake wiring can be accessed under the front couch. There is a removable inspection cover in the wall right behind the umbilical connector.

[TG Twinkie]

Have to chime in here. If the breakaway switch is open and you have a good ground on the brake coils and good connections on the +12 volt side of the circuit. You should read 12 volts when you check it at the 2 wires coming out of the breakaway switch. Given that they are still connected in the circuit as normal.
The wire coming from the brakes will be at the same potential as ground/common, it's refered to as stand at ground/common. Since the breakaway switch is open there is no current flowing thru the circuit, therefore no voltage drop across the brake coils (ie no brakes applied)
Conclusion. Since the wire coming from the brakes is at ground/common potential and the battery side of the breakaway switch is at +12 volts, you will read 12 volts across the switch.
You can test this by using a 12 volt light bulb connected in series with a switch and wired up to a power source. Read across the switch when it is open = 12 volts. Switch closed = 0 volts across the switch 12 volts across the light.
When the breakaway switch is open the voltage drop is across the switch ie 12 volts. When the switch is closed the voltage drop is transfered to the brake coils because of the electrical current demand thus 0 volts across the switch 12 volts across the brake coils.

[Splitrock]

Before I connected power to the brakes on my trailer, I tested the lead to see if the circuit was open. The meter showed a closed circuit, so I assumed I had a short. I individually tested all 4 magnets and they were all open and the lead was open, but tested together again showed a load on the circuit. I hadn't figured that each magnet set up a load and together they added up. I powered the circuit and all 4 magnets worked fine.

[CanoeStream]

Breakaway brakes are required in highly variable fashion across the country. Seems the usual starting trailer weight is around 3000# -- may be less and sometimes twice that amount. See the attachment from boatwheels.biz

A functioning battery in the trailer is required for breakaway brakes to work. Be wary about pulling the breakaway lanyard. It will start sending current to the brake solenoids and those are said to begin burning out within 5-10 minutes of applied current. [on edit: pull the lanyard out to test but reinsert it within a minute or two]

Each of your trailer wheels should have an electric brake. You can diagnose each one individually with little more than a compass. Turn a plastic pail upside down and stack some wood (cardboard boxes?); place the compass at the axle as close as you can to the brake drums one at a time. You don't have to remove the wheels if you place the compass on the inside (toward the midline).

Use a mirror to watch the compass needle as you have a helper pull the lanyard. Watch for some needle swing and then have your helper insert the lanyard male back in place right away. The swing isn't much and the compass has to be real close. But one by one you can determine if the brake magnets are functioning.

[raebaker06]

found the trouble guys. Thank you for all the info and direction.
The trouble lay in that I repaired the battery box and in doin so I twisted the Positive cable and the strand broke and left only one strand conected. I qiuck repair and a new connector fixed all the problems..
Being an electronic expert since 1946 I knew this all along Heh heh.

Just old and thick.

Rae Canada

[TG Twinkie]

@ canoestream; If you can burn the brake coils up by pulling the break away pin and leaving the +12 volts to the coils for too long. What do you do when you are stuck on a hill in traffic for an extended period of time? Is the break controller smart enough to know whether you are stopped or moving?
I don't believe the brake controller puts out the normal 12 volts that the break away switch applies. I think most are a pulsating voltage at a lower level of potential.

[Silver Goose]

Originally Posted by TG Twinkie

...I don't believe the brake controller puts out the normal 12 volts that the break away switch applies. I think most are a pulsating voltage at a lower level of potential.

You're correct. The breakaway switch applies full battery voltage to the magnets to stop the trailer ASAP. Depending on the controller, many are adjusted to provide a maximum of 6 - 8 volts in a panic stop. Some of the smarter ones drop to about 2 volts once the inertia indicates all has stopped moving to provide a hold current to the brakes as when waiting for a green light.

[raebaker06]

Thanks to one and all your indulgence has been one of joy. Thank you again

I will call upon you when I have mead another stupid mistake.

Regards

Rae Canada

[raebaker06]

Thanks a bunch guys your indulgence has been a joy.

I will call upon you when I have made another mistake.

Regards

Rae Cabada