# Connecting a trailer brake controller in a GMC Envoy

**URL:** <https://community.cartalk.com/t/connecting-a-trailer-brake-controller-in-a-gmc-envoy/4752>\
**Category:** Maintenance/Repairs\
**Created:** [September 17, 2007, 6:59pm UTC](https://community.cartalk.com/t/connecting-a-trailer-brake-controller-in-a-gmc-envoy/4752 "2007-09-17T18:59:34Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Al\_Evans](https://avatars.discourse-cdn.com/v4/letter/a/e9bcb4/32.png) [@Al\_Evans](https://community.cartalk.com/u/Al_Evans)\
**Post date:** [September 17, 2007, 6:59pm UTC](https://community.cartalk.com/t/connecting-a-trailer-brake-controller-in-a-gmc-envoy/4752/1 "2007-09-17T18:59:34Z")

</div>

My Envoy came with a towing package & there is a wiring harness under the dashboard on the driver’s side. The wires terminate in a gray connector about the size of a pk of cigarettes. Snapped into the connector is a small black box part #12450284. It also says on it : 2/4 w/opt Trailering & DOT ACDTRIDON (1564B5).  
  
 To install a trailor brake controller, Do I remove this black box & attach the brake controler in it’s place or leave the box there & cut the brake controller wires into the wires going to the gray connector?

---

<div class="post-metadata">

**Author:** ![TwinTurbo](https://avatars.discourse-cdn.com/v4/letter/t/8baadc/32.png) [@TwinTurbo](https://community.cartalk.com/u/TwinTurbo)\
**Post date:** [September 17, 2007, 8:17pm UTC](https://community.cartalk.com/t/connecting-a-trailer-brake-controller-in-a-gmc-envoy/4752/2 "2007-09-17T20:17:17Z")

</div>

That is a heavy duty flasher module GM installs to accomodate vehicle AND trailer lights. I would think that any trailer brake controller from a reputable company would not require any wire cutting and would have explicit instructions on how to install it. Do you have a manufacturer and model number for your trailer brake controller?

Here’s a website dedicated to the Trailblazer/Envoy platform. There’s quite a few smart folks over there that are very familiar with this platform. Click on this link to go there: [http://forums.trailvoy.com/index.php](http://forums.trailvoy.com/index.php)

---

<div class="post-metadata">

**Author:** ![Roadrunner](https://avatars.discourse-cdn.com/v4/letter/r/d2c977/32.png) [@Roadrunner](https://community.cartalk.com/u/Roadrunner)\
**Post date:** [September 18, 2007, 12:56am UTC](https://community.cartalk.com/t/connecting-a-trailer-brake-controller-in-a-gmc-envoy/4752/3 "2007-09-18T00:56:53Z")

</div>

In front of your left foot is a box with a cover.

Remove the cover and plug one end of the harness into it.

The other end goes to the brake controller.

I use a Prodigy bc (highly recommended) in my Tahoe and found it’s a simple hook-up with the GM trailer wiring harness from the bc to the box.

Make sure you mount the bc according to instructions though.