Trailer brake help needed!!

[3 Squids]

Hi guys. I have a trailer with strictly electric brakes. It's a brand new trailer and the brakes seem to be fine on the trailer end. If I pull the emergency release cable they lock up. If I use a 12v source and touch the trailer cable in the 2 correct spots the brakes lock up.

Here's where I am lost. I have a 02 F-250 with the factory tow harness. Factory brake controller harness and a new Prodigy controller (I bought this as I believed the Reese one I had was the issue). When the trailer is plugged to the truck the brakes do not function. When it's hooked to the truck and I pull the safety cable they will not lock. With the safety pulled and then I unplug the 7-pin connector the brakes will lock. If I plug the 7-pin back up the brakes stayed locked.

On the truck at the plug when the box is turned all the way up and brake pedal pushed I get a 11.5v reading using the trailer ground pin and trailer brake pin. Voltage drops as it should when I lower the setting on the controller.

I've checked and made sure everything is grounded well. I made a jumper wire from the truck plug ground to ground to the pigtail and used another jumper in the trailer brake slot from the trailer. Now here's where I'm stumped and maybe it's something common. With the control box turned all the way up and the brake pedal pressed, the trailer brake terminal and both left and right brake light terminals have 11.7volts with the multimeter. If I touch the brake jumper wire to the trailer brake terminal on the truck nothing happens. If I touch it to either of the brake light terminals the brakes engage. All 3 have + voltage. What am I missing?

[spareparts]

Have you pulled the drums and looked at the magnets? Apply the brakes and see if the magnet will hold a wrench. Keep in mind, the wheels need to be rolling for the brakes to apply. Has the trailer been put in salt water? We fix trailer brakes with a torch around here,

[Destroyer]

Originally Posted by 3 Squids

What am I missing?

Squidder, please don't take offense at this reply. I know it sounds flippant and smart a$$ed, but really it's not. As I see it, in answer to your question above about what are you missing... The answer is simple. ....Surge brakes.

It's the old KISS principal again. Keep It Simple Silly. Surge brakes are mechanical/hydraulic. No magnets to go bad, no wires to corrode, no tearing your hair out testing 7 different electrical connections, etc, etc. Just straight forward physics As long as you keep your brakes clean (Disk or Drum) and you check your brake lines and fluid about once a year they will reliably stop your trailer every time. Think about it. There's a reason that brakes on cars are hydraulic and not electric. They simply work. And really, after all is said and done, isn't that what you want?

[3 Squids]

I should of noted this is not a boat trailer. It's my enclosed 14' work trailer. Like I said it's brand new. And the magnets seem fine. Like I said if I just use jumpers from a battery they'll lock the wheels right up (I jacked one side up). It definitely seems on the truck side. Just so confusing that if I apply the 12v (or whatever the brake box is putting out) to the brakes nothing happens but the voltage from the brake light pin activates them. My buddy is supposed to come by this weekend with his truck with a box in it and try it out. I guess that'll really tell me if it's the truck or trailer.

[phatdaddy]

Squids, not real familar with electric brakes, so all this is a guess. I'd verify that the 7 pin connector is matching the trailer. Do all the lights work properly? That would eliminate 4 wires (right, left, running,& ground). That would leave 3. (Brake, 12 vt constant and reverse). If everything is right on the trailer, verify the truck. We had a new flatbed trailer at work that would tap the brake everytime you turned the right blinker on.

If all that checks out fine, check voltage while under a load. Sometimes those 11.5 's will drop when put to work. Also might try checking without the trailer hooked to truck, this will eliminate any stray grounding through the coupler, which can confuse the issue.

My tahoe only has the 7 pin connector and i had a bad adapter, 7 to 4, that drove me crazy.

Good luck

[oteps]

Sounds like u have a truck wiring problem. If its a new trailer go back to where u bought it and see if they will let u hook up to another trailer to make sure its not the trailer. If u need any info from the truck side let me know, I have a 99 f350. wiring should be similar.

[Destroyer]

They should all be standard Squidder. 7 pin plugs are just like 4 pin plugs. Industry standard wiring. And usually any problem can be traced to a poor ground someplace.

Here's a wire layout of what should be going where. Hope it helps.