[SEL] Semi OT - Trailer question

[bill at antique-engines.com]

Not to doubt your work, but sounds like ground-loop condition.....
Double-check the grounds - disconnect the brake wire if you can and see if
the lights dim.
Wires can build resistance where they enter the terminal - especially
"crimp-on" connectors. You can get a thin layer of oxide you can't really
see down in there.
You can measure that with a voltmeter.
Turn on the load - lights for example.
Connect the meter so one lead is on a GOOD clean ground, the other on the
ground wire just ahead of the terminal or connection. Resistance in a
connection will show a voltage across that connection.

If a ground wire has a loop terminal where a bolt or screw holds it to the
frame, for example, put your meter on the frame/ground and where that wire
enters the loop terminal. Should see NO reading at all.

You are looking to measure voltage drop across a resistance. No
resistance, no voltage to measure - they both should be the same, no meter
deflection.

Bill

> Although I do use my trailer for hauling my engines & tractor - I hauled
> out
> my 16' flatbed trailer today in preparation for summer shows, & noticed
> something peculiar. All the running lights work fine, as well as the brake
> lights, but when the lights are on, the electric brakes are engaging.
> Enough
> that when I turn the lights on when pulling it, I can really feel the
> brakes
> grabbing, so they are engaging all the way. Any ideas? I figured all the
> grounds & other connections were clean & tight, since the lights worked.
> But
> could it be a frayed wire touching the body & feeding back into the brake
> wire? But that would blow the fuse, right? Got me stumped.
> Thanks for the help,
> John
>
>
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