How to Diagnose a Nonworking Brake Controller After an Engine Swap

Updated 07/01/2021 | Published 06/30/2021

Question:

I had my engine replaced now my brake controller is not working

asked by: Penny S

Expert Reply:

Finding the issue and testing what could be causing your issue will depend on what vehicle you have, how it was equipped, if the fuse box was removed at any point or replaced, and how everything was rewired after the engine was reinstalled.

First, check the black wire going in to the back of the controller with the vehicle on. If you are not getting any power, you will need to check your trailer brake controller fuse for a vehicle that has a factory towing package and port under the dash. If this fuse is good, you will need to go back to the place that replaced your engine to have them diagnose and fix the short or break in the wire that must have happened during the engine install.

If your vehicle does not have a port under the dash and an aftermarket set up was done, you will need to follow the power line to the circuit breaker between the controller and the battery. Odds are this will need to be replaced and it should get you back up and running. If it does not and you are now getting power to the back of the controller, Something may have overloaded and shorted the controller. At this point, the controller will need to be replaced.

expert reply by: Lazer S