I got my truck wired up for a brake controller , all new wiring and connector. Using a test light, all connections work on the truck connector.

I backed up to my neighbors trailer, that is wired good, DID NOT HOOK it up to the ball (didnt have one on) and the brake lights and trailer brake didnt work. Does the truck have to be hooked up to the trailer with the hitch in order for the brake lights and brake to work? TIA

 

It shouldn't have to be, but I have seen them grounded thru the hitch. In which case, yes, it would need to be hooked up.

 

"grounded thru the hitch" which happens to be a very bad idea. The brakes may have been working. You can hold a compass next to the hub on the trailer wheel and have a helper step on the brake. The needle will turn towards the wheel as the brakes come on, as they are magnetic. You can also ussully hear them buzz.

Also, look in the underhood fuse box and make sure your trailer fuses are in place and good.

 

I didn't and don't endorse grounding thru the hitch, but I have seen it done.

 

I've been working on and building trailers since the early 1980's and I've never thought of using a compass. Thanks for that tip 1-2-3!

 

You can also use a compass to check for problems in the wiring. In 1819 Hans Christian Oersted discovered that a magnetic field surrounds a current-carrying wire.

 

the last trailer I bought had the "ground thru hitch" set up...it was the first thing I changed. That is a horrible set up...

 

Are you grounding the test light to the ground pin on the truck's trailer connector, or did you ground the test light to the bumper or something? You may have a missing or open ground in the truck's connector. Do the lights and brakes work when the trailer's plugged into your buddy's truck? Did someone *creatively* wire the trailer side connector to match the way they wired a specific truck?

The bottom line is that everything should work without the trailer hitched to the ball. Dim or intermittent lights are one thing, but you don't want to rely on a ground thru the ball when brakes are involved.

 

I tried to check the neighbors truck but couldnt get a good enough ground on his truck to check his connector out, using his test light.

I used my test light and got a good ground off the hitch bolts from underneath and the connector checked out fine.

My friends truck works fine and his trailer works to perfection, which I why I went to his trailer as I knew it was good.

My thought was that it maybe had to be hooked up for it to work. Its just not makin any sense to me.

 

Check continuity between your trailer connector's ground pin and those hitch bolts. The ground is either not connected to the pin in your truck, or the trailer is wired differently than standard.

 

Check continuity between your trailer connector's ground pin and those hitch bolts.

Or, is your truck (or the trailer for that matter) wired the standard way? Here is a link to the wiring standards. Scroll down to find the connector you've got.
http://www.etrailer.com/faq-wiring.aspx

 

Ok, I went out and checked it out with the test light. Everything works with the exception of the brake lights at the connector. Neither side lights up with the test light and the brake appllied to the truck (actual brake lights on the truck working). These are the connectors at 9 and 3 oclock position. Any ideas on that? 7 pin flat set-up.

 

Check the truck harness where it connects in the back of the plug. Corrosion eats away the wires and breaks the connection.