Odd brake controller problem

[Wishbone51]

I traded in my old TT and purchased a 2017 Jayco. On the way in, while towing my old TT, the trailer brakes worked just fine. On the way out, it didn't. Took it back to the dealer, and they plugged in a 7-way tester, and we couldn't get the electric brake pin to light up. The fuse is fine.

Later, at home, I connected a volt meter between ground and the electric brake pin on the 7-way on my truck, and it's showing a constant 12V. When I unplug my brake controller, the voltage goes away. The Google says that this means the brake controller is probably shorted.

1) What could cause this between me dropping off a trailer and picking up a new one? I would think that a short in the trailer brakes would cause the fuse to blow, unless that was what destroyed the brake controller. They *said* they tested the trailer brakes when they adjusted my hitch.

2) If the electric brake pin was 12V, wouldn't that lock up the brakes on the trailer? I know it was rolling nicely, because I was getting better gas mileage on the new trailer (1000 lb lighter)

3) Why would their 7-way tester not show a voltage when my multi meter did? I tested it with the turn signals, and it was fine.

[Sjm9911]

Just some more info. On mine it was reading fine untill i need to break at a higher level then the voltage wasnt enough to activate the magnets, and i got a low voltage reading on my break controller. I hooked mine up to my old pop up and it worked fine, so it was the new TT TT breakes. So , even if it reads ok when hooked up or slowly moving , check it on the road also.

[Jebby14]

make them put anything they say in a report or record it.....

sounds like their pdi was skimpy at best. this is a safety issued id be making a BIG deal over. Who knows maybe they will make it right, not likely

[Wishbone51]

Hooked up my truck to a friend's trailer, and the brakes are working just fine ... Dealer was blowing smoke when I called them yesterday, and they said the braking system on the trailer is just fine. When I go to pick it up, if it's still not working, I'll insist on hooking up to another trailer to show them that there's nothing wrong with my truck.

[mkirsch]

You need Amps to actuate the brakes, not just Volts. You can read a voltage, but if the connection is high in resistance, you won't get adequate current flow. As soon as you connect the brakes, the voltage basically goes to zero.

What you are measuring, probably, is a sensing voltage that the brake controller is using to determine if the trailer is connected.

[Sjm9911]

Check the grounds first. Then start looking at the new TT, because it worked on the old one. Does your break controller show low voltage when the breaks are applied? Some do , some dont. I had to rewire my breaks on my TT. Kept showing low voltage and not activating the breaks.

[Wishbone51]

Thanks .. I edited it to say "electric brake"

[Lynnmor]

There is no e-brake pin, you'll have to rewrite this so it makes sense.
The term "e-brake" usually refers to the emergency brake system.

The brake pin on the truck may show voltage under no load, but that voltage will go away with the slightest load, but that depends on the controller used.

I would check for continuity between the brake pin on the trailer and a trailer ground.