bing tracking image

How to Install a Brake Controller on Chevrolet / GMC 1999-2006 Pickups

Vehicles with Factory Installed 7-Way

If you are attempting to install a brake controller on a Chevy/GMC truck (1999 - 2006, including 2007 classic) and your vehicle is equipped with the factory installed 7-Way trailer connector, the only part needed to install the brake controller is the unit itself. The manufacturer provides a brake control adapter that connects to the brake controller and plugs into the vehicle's electrical junction box. This junction box (shown below) is located on the driver's side below the dash, left of the brake pedal. If the factory brake control adapter cannot be found, we offer a replacement (for model years 1999-2002 use 3025-S, for years 2003-2006, including 2007 Classic models use 3015-S). After mounting the brake controller in a place that is easily accessible, your installation is complete.

Custom Fit Brake Controller

Brake Controller Product Image
Locate Brake Controller Adapter Plug Image
The brake control adapter plug is located in the electrical junction box on the driver's side, left of the brake pedal.
Close-up of Electrical Junction Box Image
This close-up of the electrical junction box with the lid off shows several available slots. The brake control adapter is plugged into the second slot from the left on the top row.

Vehicles without Factory Installed 7-way

Step 1 - Install brake controller:

Hardwire the open wires of the brake control adapter to the wires on the brake controller. Plug the other end of the adapter into the electrical junction box (see above). Mount the brake controller in a place that is easily accessible.

Step 2 - Under the Hood:

Remove Bracket in Corner Image
A: Remove the bracket in the corner closest to the driver.
Remove Top Cover from Accessory Fuse Box Image
B: Remove the top cover of the "Accessory Fuse Block."
Remove Lower Cover to Fuses Image
C: Remove the lower cover to the fuses.
Locate Blue and Red Wires Image
D: Locate the blue and red wires. These are normally located next to the fuse block on the cab side. The blue wire has a plug on it, the red wire has a ring terminal on it.
Place Red and Blue Wires and Clip Image
E: Place the red wire over the closest positive post (B). A green 30 amp fuse is needed in the location nearest the positive post to power the brake controller. A smaller brake controller may require only a 20 amp fuse. Consult the brake controller installation instructions and the vehicle's owner's manual. Next, clip off the connector on the blue wire (A).
Placing Gray Double Bonded Wire Image
F: The installation kit provides a gray "double bonded" wire which is really two wires in one. Connect the white wire in the gray housing to the blue wire under the hood. If a hot lead is also needed connect the black wire (shown in red for clarity) to the other auxiliary positive post. A 40 amp fuse needs to be placed in the last spot, closest to the post, to power the hot lead (see picture). If this post is already in use, you may connect the hot lead directly to the positive side of the battery via a 40 amp circuit breaker (provided in kit). After the connections are made, route the remaining length of the double bonded wire to the back of the vehicle, where it will be attached to the 6 or 7-way adapter (provided). Usually the wire is run either inside or above the frame on the driver's side of the truck. Once run, connect the white (brake) and black (hot) to the blue (brake) and black (hot), respectively, on the back of the 6- or 7-way adapter.

Step 3 - The Trailer Connector:

Plug 4-pole into 6-way or 7-way adapter Image
A: If the vehicle is already set-up with a flat 4-pole trailer connector, then plug it into the 4-pole on the back of the 6- or 7-way adapter that comes with the installation kit. The white wire (ground) coming out of the back of the adapter needs to be attached to a substantial grounding point on the frame. After mounting the new 7-way or 6-way connector, installation would be complete.
Find Necessary Wires Above Spare Tire and Wire Colors Image
B: If no trailer connector has been provided, the necessary wires can found above the spare tire. The yellow wire is the left turn and brakes, dark green wire is the right turn and brakes, brown wire is for the taillights, and white is the ground. Often if the loom is cut back, two more wires will be found. The light blue wire provides a lead for a camper shell brake light. The other, a light green wire, is for the reverse lights.
Connecting the Wires Image
C:Connecting the Wires. First cut off the 4-pole on the provided 7-way or 6-way adapter in the installation kit. Quick splices are provided to connect to the wires above the spare. The green wire is connected to the dark green wire on the vehicle; the yellow to the yellow, brown to brown. The white (ground) on the adapter can either be connected to the white (ground) wire above the spare, or it can be grounded directly to the frame.
After installing the mounting bracket with your 7-way or 6-way trailer connector, the installation is complete.

Jose C.


Howdy, I have a 2006 Chevy Silverado 1500 with a 7 way factory plug. It seems I have a blue wire with no place to connect it to, it has a connector with 1 pin, I also located the red wire for 12V power but I just need to get a 40A fuse for it. Is the connector for the blue wire una different location or will I need to do some wiring to connect my trailer brakes? Thanks!

Etrailer Expert

Mike L.


@JoseC I assume you're speaking of the blue wire in the engine compartment next to the the fuse box. If so, that wire carries the output from the brake controller. You'll attach a length of # 10-1-1 wire long enough to run under the vehicle and attach to the brake pin on the 7-way.

Mike S.


Hello, I have a 2004 GMC Sierra 1500. I bought a Reese pilot brake controller and I'm not getting any power to it after plugging it in. Any suggestions why I'm not getting any power !!? I do have power to my 7 blade, and all the lights and signals work on my camper. Any help I'd appreciate it. Thank you

Etrailer Expert

Mike L.


@MikeS You're very likely missing the green 30A fuse in the distribution box under the hood on the inside driver-side fender. In the help article you'd checked out, you can see the fuse location in figure 'E' to the right of the power post labeled as 'B'. Hope that helps you!

Mike S.


@MikeL Thank you for your help. My fuse box doesn't exactly look like that. I have square fuses. I believe J series. I also have a 30 amp closest to that post like in the article. I never ran that gray wire to the back of truck to the 7 blade, because I already have power to the camper just no power to the controller. If I have to do that, where do I run the black wire too because I already have a black wire connected to the 7 blade ?

Alejandro V.


Hello, I have an 06 gmc Sierra with a factory 6 way. I have power to my brake controller and everything seems to be working fine until I plug in the trailer. With the trailer plugged in I still get a reading that no trailer is connected. What am I doing wrong?

Etrailer Expert

Mike L.


The most likely cause is a dirty, corroded or damaged trailer connector, either on the vehicle or on the trailer. Closely examine both connectors, look for green or white corrosion on the pins and sockets. Replace the connectors if necessary. If that isn't the issue, check the wiring feeding the brake assemblies. Each assembly will have two wires exiting it, one connecting to ground, the other to the brake output circuit. Make sure these connections are secure and not corroded. A less-likely but still possible cause could be worn brake magnets. Pull one of the wheels/hubs and check the face of the magnet that rides against the armature surface of the brake drum. If the face of the magnet is worn to the point where the copper wire inside the magnet is showing, then the magnets (or brake assemblies themselves) will need replacement. We hope that helps! We'll also link you to a troubleshooting article that you might find helpful.

Erik H.


I have 2001 Chevrolet Silverado 4x4 I have Curt Discovery brake box I took out of my 3006 GMC Yukon I bought a adapter to plug in it n my 2001 and I hood up the red wire that was under the hood to positive post! I have a red light that comes on if I push the slide on the brake box but my security light comes on in the dash nothing if I push the brakes! Thanks

David B.


What adapter did you get? It appears to me that something is wired wrong or shorted out.

Ozzie V.


Hi. I got 1999 Chevy Silverado and I don’t have power on the brake blue wire I got a7 pin plug And the rest of the wires only gift me 11v except for the auxiliary that one gift 12v And the trailer turn lights are very dim And nothing else work on the trailer Can you please help me

David B.


Ozzie, thanks for reaching out, let me direct you to an answer page that will help you troubleshoot the blue wire issues you are having. For your dim lights I would think that is a bad ground point or a damaged/shorted wire. Check all the fuses and ground points, and work your way down every wire checking for damage. Let me know how all the troubleshooting goes and if you need anything else I'll be here to help.



Sports and Recreation

Trailer Parts


What our customers are saying:

"In these days of customer "no service" I am usually disapointed when doing business with people I don't know. It was refreshing doing business with you. I'm impressed!"

Watkinsville, GA

Popular Vehicles