Pull the leads off of that battery and touch the leads to a jump box or something better. It may have 12V on a DMV, but no amps to push.

You need the little black box that wires into the Brakerite controller on the trailer for the GM to work..... Call myco they have them in stock like $80

Pat

The factory brake controller of an 09 will not work with EOH. The EOH system does not have resistance for the controller to read so it will not activate. Electric brakes have resistance through the magnets so the controller will read a hook up and send out a brake signal.

You can get a new controller that will work with both EOH and Electric brake systems. If you have both kinds of trailers that would be the best way to go. If not then you just need to get the EOH to work with a controller.

Some have wired in electric trailer brake magnets on the tow vehicle so a regular Electric brake controller will see the resistance and send out a signal that the EOH can use. I don't care for that method but it works.

Same as above, I don't think your controller is compatible with electic over hydraulic. I had to abandon the built in controller and install an aftermarket. I couldn't figure it out, so I took truck to trailer shop and paid for install. 2010 Chevy 3500 HD They also had to do something with the brake fuse circuit. Has something to do with charging break away battery. If you pull break away switch, break pump makes same lound noise as if you were applying breaks. I screwed up and moved trailer around enough before I if figured out that it wasn't working that I damaged pump motor and ruined battery. Expensive and dangerous. Initially I wasn't worried because truck can easily stop empty trailer.

Andy

My mechanic just text me and said he installed the "SD Module" on my trailer so that it works on the truck... 2008 GMC Sierra 2500... didn't touch the truck, we have had to do this on 2 different Myco's over the years for the same truck.

Hope this helps!!

Pat

This trailer already has the black box on it. My 2008 GMC never works with EOH brakes either. I was told to add another controller in the truck. The factory unit only seems to work with electric brakes not EOH.

Check the battery on the trailer. If it's not engaging the brakes when you yank the rip cord, the battery is bad OR the brake system is already damaged.

Plug it into a Ford or another truck with a MaxBrake (best one on market) or a Tenkosha.

Talked to both Myco and BrakeRite and it ended up being a bad SD module on the trailer. They were both great to work with - gave me the test procedure and pointed right to the bad part. Thanks for all the help everyone.