Vehicle Battery Died and Trailer Brakes are Locked Up

Question:

I had this Primus IQ brake system and 7 point wiring harness installed and set up professionally into our 2010 Jeep Liberty two years ago when we bought our tent trailer. Works great. Drove from BC to Ontario twice and many camping trips in between. Last week however, while camping, the brakes locked up and we couldnt move the trailer off the camp site. We towed it there no problem, but couldnt get the brakes to unlock the next day when we needed to leave. We unplugged the trailer harness and drove it home With no trailer lights or trailer brakes. rolls along fine when the harness is unplugged. locks up tight when I plug it in. The only thing out of the ordinary that happened the night we were camping was, the truck battery died. We were sucking power from the truck battery until the truck gave a couple of loud beeps and died. After waiting over night, the truck turned over, I reset the clock and all seemed well. Until we tried to move the trailer. No idea if one had any thing to do with the other. Have you heard of this happening before? Is there a reset option on the Primus IQ? Any idea on how to get my brakes to unlock?

asked by: John

Expert Reply:

I have not heard of a dead vehicle battery causing trailer brakes to lock up, but that would not be the weirdest thing I have heard of when it comes to trailer problems.

The first thing I would do is unplug the brake controller for a few minutes and plug it back in. This will reset the brake controller. After you reconnect the brake controller, I would use a circuit tester, like part # PTW2993, to test the 5 o'clock pin in the trailer connector at the back of your Jeep Liberty (see photo). This pin should only have power when you hit the manual override on the brake controller or step on the brake pedal. It should not show power any other time.

If there is no power on this pin, then resetting the brake controller may have fixed the problem. If you still have power on that pin, then go back to the brake controller and cut the blue wire about 6 inches back from the brake controller and test it again with the circuit tester. If you still have constant power, then the issue is the brake controller, and it will need to be replaced. If you do not have power there, then the issue is somewhere in the wiring between the brake controller and the trailer connector. Somehow power is reaching the electric brake output wire. I would inspect the wiring to see where there could be a potential issue or have the installer inspect the wiring if you are not comfortable doing this yourself.

I have attached a few brake controller help articles for you to check out.

expert reply by: John H