George,
Your problem is that you're assuming that whoever wired your truck and whoever
wired the trailer were in agreement as to what pin on the connector should have
a certain function. <<grin>>

Throw out that thinking and start over.

Use a test light to make a diagram of your truck connector. (NOT a meter!)

Connect a battery to trailer ground, then touch the positive lead to each
connector pin in turn and make a diagram as to function. Note, you may have
smoked the brake magnets by leaving the breakaway switch closed like you did;
those magnets aren't meant to be continuous duty. One of the trailer pins will
be "hot" because it's connected to the trailer battery for charging purposes.
If your truck doesn't have battery power at the connector, you should
disconnect this wire at the trailer connector so as to not backfeed things like
you did.

Once you have the 2 diagrams made, compare them to see where the differences
are; you'll no doubt have to rewire one or the other.

There ARE some standards, and you might want to check your connectors to see if
either meet them. http://www.championtrailers.com has diagrams for a couple of
the popular connectors. Most later A/S trailers use the "RV" connector which is
a 7-pin flat-blade job. Another popular one uses 7 round pins.

Of course, if you have another trailer (boat, utility, or...???) you'll want to
probably change the A/S to match what you already have.

George W. Moore wrote:

> Hi;
> I am a new member from Orofino Idaho and I just acquired an old
> Airstream 22' trailer ( 1963) and am having trouble figuring out the
> wiring. The trailer has a 6 prong plug and appears to have the wires
> properly attached to the plug, that is , I checked continuity with the
> lights and the pins and they appear to located on the proper pins. However,
> when I plugged in my truck the brake lights and left and right turn
> signals worked, but even when the truck lights were off the stop lights on
> the truck came on.
> After I got the trailer home I checked the pins and found that the
> stop light pin was hot with 12 volts from the onboard battery. I thought
> that maybe the breakaway switch was the problem so I disconnected it and
> still found 12 volts on the stop light pin. I left the pin out of the
> breakaway switch and found that the battery had been run down completely by
> the next morning, so I think that that indicates the brakaway switch is
> allright.
> Incidentaly with the stop light pin hot (12 volts) I would have
> thought that the stop lights would come on,( on the trailer) but that
> wasn't the case.
> By the way I didn't have a controller for the brakes when I brought
> the trailer home so am not sure the brakes are working.
> I don't think that the stop light pin on the trailer should be hot
> and don't know how that could happen. The previous owner claims no
> problems, if so then, something must have just happened or else this is
> proper.
> Can anybody give me some advice on the proper wiring of this small
> old triler and hopefully give me some pointers as to how to solve this
> problem.
> Sincerely;
> George Moore