2015 Chevrolet Colorado: Installing a Trailer Brake Controller
March 2, 2015
We bought our 2015 Chevrolet Colorado with the Trailering Package because we wanted it to be ready to do some towing. The 3.6-liter V6 is good for only 3,500 lbs. without this option, but that jumps to 7,000 lbs. when the package is present.
Among other things, the trailering package pre-wires the truck for a 7-pin trailer connection, the kind that supports electric trailer brakes and trailer battery charging via the alternator when on the move. It's all built into the wire harness and fused in the under-hood fuse box.
The only thing missing is an electronic trailer brake controller. The current-generation Silverado options list offers a built-in one, but that option is not available on the Colorado.
This isn't that unusual. Built-in trailer brake controllers in full-size trucks are a relatively new development. So we simply did what truck owners always did up until a few years ago: We installed our own.
In the recent past, pre-wired tow-package trucks would come with a small sub-harness that was stuffed in a bag in the glove compartment or hidden under a seat. It'd have a connector on one end and bare wires on the other. The idea was you'd splice you're trailer brake controller to the bare wires and plug the connector into a waiting receptacle under the dash.
I went looking for something like this and ran into a roadblock.
I looked everywhere in the Colorado's cab and found nothing. No sub-harness stashed in a bag, no likely waiting connecter under the dash. I read through the towing section of the owner's manual and found no mention of the topic. As a last resort I went to my local Chevy dealer's parts counter to see if the mythical sub-harness was something I had to buy. He came up with nothing.
Frustrated, I emailed a Chevrolet PR guy. He sent me a PDF of the owner's manual and directed me to page 9-64 in the towing portion of the Driving and Operating section. The answer was as plain as day, with an illustration, too. How did I miss that?
I looked at our printed copy once again. The specific paragraph and illustration I needed on page 9-64 simply weren't there. Turns out the PDF copy he sent was the second printing, and our truck's printed copy was a first printing. The newer one is currently being shipped with new trucks, but early adopters like us can find it online at Chevy's website.
It turns out the wire harness I was looking for is hidden behind the kick-panel down by the parking brake pedal.
The kick panel and step plate are one piece, so you must first pull straight up from the back edge and work forward.
After the flat portion is free you pull straight back to undo the forward-facing clips that hold the kick panel in place.
The small bundle of four wires is easy to spot, and they have molded-on protective ends. It's important to know that the red power supply wire is an always-on power feed.
We need to disconnect the battery at this point because we're going to be grafting onto these wires.
These connections will live in a dry, low-vibration indoor environment that's behind a protective kick panel, so I was comfortable with crimp-on connectors. Note that the red (power in) and blue (electric brake power out) wires are made of heavier-gauge wire than the black ground wire and white brake light signal wire.
Josh came over with some wire and shrink tubing, and together we built up a small sub-harness of our own. We added connectors and decided on a Velcro mount so we could remove the trailer brake controller when not in use.
The trailer brake controller manufacturer may use different color codes than Chevrolet, so it's important to read the wiring diagram and carefully match them up by function.
Tekonsha made the Voyager controller we used, and it defines input power as black, trailer brake output power as blue, ground as white and brake light signal trigger as red. Josh and I decided to hide the mismatch here at the permanent connection so users could color-match the connectors we added to make the controller easily removable.
You must remember to slide any shrink tubing pieces you plan to use over the wires before you make the final crimps, of course. There's no adding them later.
There's plenty of room to tie-wrap the new wire bundle in place before you replace the kick panel.
Our color-matched connectors will make it easy to remove the controller and tuck the wires under the dash when not in use, but the always-hot black one and sometimes-hot red one (remembering the Tekonsha convention) will need to be covered.
A little spiral-wind plastic makes the final result look tidy.
Josh and I needed to get this controller up and running on short notice because of the Ram's unexpected dealer visit. We may upgrade our improvised under-dash connector to a single plug if we can find a suitable one that doesn't require pro tools to install. And while I've had success with Velcro before, the surface is slightly curved here. We may need to use Tekonsha's supplied bracket and drill some holes.
Dan Edmunds, Director of Vehicle Testing