Troubleshooting Brake Controller that Seems to Drain Vehicle Battery When Towing

Question:

I have a 2013 Ford Escape. I have a CURT Discovery brake control and a 7 pin attachment into the 15’ T@B trailer. The car battery dies the day after getting to a campsite. Ford has not found any issues with the car and it’s a new battery The trailer itself has checked out without problems or electrical issues I disconnect the trailer from the car upon arriving at campsite. I turn off interior car lights and dim dashboard to minimize power drain when opening and closing doors for unpacking car My suspicions is it has something to do with some kind of drain or load on car battery while driving to campsite The brake controller was installed by Rack N Road. How do I figure out what is draining my battery. FYI Car battery is fine when not towing. It never dies other than after towing my trailer

asked by: Sabina H

Helpful Expert Reply:

It sounds like the issue is with how the brake controller's black wire is connected to the vehicle battery. Somehow this connection seems to be preventing the alternator from functioning. You can verify this by using a circuit tester to test the voltage on the vehicle battery when it is running without a trailer connected. It should be around 12.9 volts. Now test it again with the vehicle running and a trailer connected. If you see it dip below 12 volts it would indicate that somehow the trailer is preventing the charging system from being effective.

Now unplug the brake controller from the vehicle and test the battery again with the trailer connected. If the voltage goes back to high 12's then you know it's the brake controller. If it stays lower then it's somewhere in the trailer wiring. For a circuit tester we then have the part # PTW2997.

expert reply by: Jameson C