Bypassing Factory Brake Controller and Installing Aftermarket Model on 2018 GMC Sierra 3500
Updated 01/05/2026 | Published 03/15/2021
Question:
I’m towing a 2019 Jayco 387RDFS Fifth Wheel with a 2018 GMC Sierra 3500HD, 6.6L Duramax, DRW, Long Bed. On several occasions, the brake controller in the truck failed. The first failure was because it blew a 30AMP fuse, which I believe is a fuse for the trailer brakes. The second failure was because of module in the GMC Sierra’s trailer braking system. The third failure was because of different module in the GMC Sierra’s trailer braking system. I get an occasional warning message regarding the trailer brakes or connection. I need a reliable brake controller that will override the factory trailer brake system in the GMC Sierra. The ideal situation would be to have an autonomous trailer brake controller that I can quickly switch to if the factory trailer brake controller fails. Second to that would be to just completely override the factory brake controller with a reliable brake controller. I’m hoping to get some suggestions.
asked by: Dave K
Helpful Expert Reply:
There isn't anything like an autonomous controller that would step up if the factory controller fails.
I'd simply bypass the existing factory brake controller. The GM ITBC, although it works better now than the earlier models has been problematic enough that Tekonsha who provides many of our aftermarket brake controllers has a technical bulletin that specifically addresses how to bypass the factory controller. Let's just say you aren't the only one that's had problems with the factory brake controller.
If you'd like the controller to stay with the trailer and not be permanently installed on the vehicle, the Tekonsha # TK94FR Prodigy RF would be a good choice. To bypass the factory controller, all you'll need to do is locate the harness feeding the factory 7-way trailer connector and peel back the wire loom and electrical tape protecting it. Locate the blue wire exiting the rear of the trailer connector and sever it, leaving a few inches of wire so you can reconnect it if need be or install a vehicle mounted brake controller in the future.
If you're wanting to tow multiple trailers, it would be more feasible to install a controller in the vehicle like the Tekonsha P3, part # 90195. The P3 is one of the controllers I recommend most often because of how good the user interface is and because of the features the controller provides. The controller provides 5 storable settings that you can used for different trailers. You'll only need to set the controller up once per trailer then toggle back and forth as you change trailers. The controller provides a full LCD display to alert you to any problems in the braking system in plain English (or French or Spanish, if you'd prefer) instead of a color changing LED or an alpha-numeric error code that you'll have to remember.
If you decide to go this route, you'll also need the # 3016 wiring harness that connects the brake controller to the connector in the junction box on the firewall behind the e-brake pedal as shown in the linked video.
I'll link to the tech bulletin that will walk you through the process of installing the vehicle-mounted controller. In a nutshell, you'll cut the blue wire of the # 3016 behind the brake controller, leaving a few inches so you can splice on a length of # 10-1-1 wire long enough to run through the firewall, into the engine compartment and under the vehicle to the trailer connector on the rear bumper. You'd sever the wire as described above, and attach the blue wire you've ran from the front.
Bill
1/5/2026
I have a 2015 silverado 2500 hd with oem brake controller installed. It is unreliable and dangerous. I spoke with your service rep. and she said the tekonsha prodigy 3 would connect directly with the supplied harness. She sent me a video of install on the same auto I have, although it did not reveal if the video vehicle had the oem controller like I do. The video reflected a pure plug and play installation and mentioned the use of a 3016 harness. Your article describes a different installation process. Please advise, Bill
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Patrick
3/4/2024
can you share the link to the video bypassing the itbc