How to Eliminate Tow Vehicle Brakes Activating When Flashers are Used With Electric Brake Controller

Updated 09/12/2011 | Published 09/09/2011

Question:

On every tow vehicle I have ever owned, turning on the 4-way flashers triggers the trailer brakes. Some have said this should not happen, but since the tugs brake lights are also the 4-way flashers, how can it NOT happen? If the brake lights are powered up, the trailer brakes come on, correct?

asked by: Dave H

Expert Reply:

When flat towing a vehicle using an electric brake controller and the flashers are turned on, the flashers will send a matching pulse back into the brake controller and light up the tow vehicle brake lights and if the brake controller is set aggressively may pulse the tow vehicles brakes.

To eliminate that from occurring you will need the Draw-Tite Pulse Preventer, part # 5501. The Pulse Preventer will isolate the brake controller from the vehicles flashers. This part will install where the brake controller is spliced into the wire from the cold side of the stoplight switch. This is typically the red wire on the brake controller.

Find the spot where the brake controller is spliced into the wire from the cold side of the stoplight switch. Then just past this (away from brake controller) cut the vehicle stoplight wire and install the Pulse Preventer inline with the yellow wire on the side that the stoplight switch and brake controller are on and the brown wire on the side going to the vehicles brake lights. This connection will stop the hazard signal from feeding back to the brake controller, eliminating the pulse problem.

expert reply by: Jeff D