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Where is the factory TRAILER BRAKE CONTROLLER located???

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7 hours ago, 2017HD said:

I have not looked on my 17 but on my 07 2500HD the guts of the controller were located on the frame behind the rear drivers wheel.


when you look on your '17, could you also give a little chase to see where the wiring harness ties in? 


There is a cluster just forward of the receiver hitch (above the spare tire) that terminates several "back of vehicle" factory harnesses, if the brake controller terminates there, we only need to find where the switch plugs in at the dash in order to (potentially) install the factory option..

-if you look in the attached image (screen shot of a video adding auxiliary bed rail lighting) the rear access point has several "covered harness connectors"..

Rear Bed Wiring Harness access point.png

Edited by rbrjr1
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On 3/14/2017 at 8:43 AM, Dave454s said:


Back when I was shopping trucks last year, ALL the W/T's I looked at had the factory controller....I only ever saw trucks WITHOUT the controller in the higher trim packages.

Don't know about '16, but on '18/'19/'20 trailer brake controller is standard on 2500 SLE and above.

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question about the aftermarket controllers..


the CURT kit on my 18 Silverado 1500 LT Crew Cab is just the switch.. it implies that the rest of the module is already connected via harness somewhere..

(is that true?)


and if it's true, then why couldn't I gain full control by just connecting the factory swtich (replacing my "cup" light bezel with a bezel equipped with the factory controller)

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  • 3 weeks later...

Your link isn’t working.. but yes.. the CURT “accessory” from GM is just the switch which wires into wires under the dash..

Why can’t someone just purchase the GM switch and wire IT into those wires under the dash?

It appears the braking control module is already installed under the bed, next to the Driver-side rear tire.
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  • 3 weeks later...

and to just push this question home, this morning, I removed the switch panel left of the instrument cluster (where the little cubby is located) and behind it, I have a wiring harness plugged into a blank space behind the cup.. (not unlike the harness plugged into the X2 connector on my factory dash switch that I replaced with the upfitter switch)


I guess it's a whole different conversation to have, but WHY include harnesses and plug them into the blanks on the back of a switch, but not pre-wire the vehicle for upgrades like "factory towing mirrors"?

Dash Harness - Trailer 1.jpeg

Dash Harness - Trailer 2.jpeg



further more, the Body Builder Electrical schematic shows that the S76 Trailer Brake Control Switch utilizes ALL 6 of the wires coming out of this harness above.


Anyone who has a PDU "All Star Edition" (or the equivalent "Texas Edition" RPO code) AND the Z82 RPO code, should just be able to swap out the switch to utilize factory towing controls..

-the Texas Edition and All Star Edition (along with LTZ/Denali) come with the K38A chassis mounted control module - Auxiliary




Am I missing something here...?

everything I've read points to "just buy the GM 84109447 switch" and you're rolling with factory towing controls..

Edited by rbrjr1
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It can’t be done there is programming involved as it shows up in the center stack for trailer gains and what not. This has been tried on here to no luck by a few good people who know the wiring and electronics of these trucks. It was a no go lol.

Sent from my iPhone using Tapatalk

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