Factory Brake Controller on 2012 Ford F350 Not Delivering Full Power to Trailer Brakes

Updated 03/22/2016 | Published 03/18/2016

Question:

Hi, can you tell me which relays would need checked on a 2012 F350 6.7 Lariat with factory TBC? The brakes work on the trailer, but does not give full braking effort, even with the hand switch. Would the Lariat have the wiring adapter to add the P3 if I get the TBC turned off at the dealer?

asked by: Tom M

Expert Reply:

I checked with an online copy of the owner's manual, and found that fuse # 22 in the fuse panel under the hood protects the power feed to the brake controller. I did not see a relay mentioned.

Do you have the gain (power) turned up all the way on the controller? Are the trailer brakes properly adjusted? Are the brake magnets in good shape? If possible, I'd recommend towing the trailer with another vehicle if possible. This will help determine if the problem lies with the tow vehicle or with the trailer itself.

You can deactivate the factory brake controller and install the # 90195 by unplugging the factory plug from the rear of the TBC, plugging the # 3034-P wiring adapter into the factory plug and then plugging the other end of the wiring adapter into the rear of the P3.

As you mentioned, you'll need to visit the dealer to have the TBC deactivated or a warning will be displayed on your dashboard.

expert reply by: Mike L