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

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:

Brake controller
Brake control adapter
- Custom adapters for specific controllers
Brake control 7-way or 6-way installation kit

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:

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."

C: Remove the lower cover to the fuses.

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.

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).

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.

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.

Charles

10/1/2025

I am having issues finding the diagram fpr the panel under the dash fpr the 6 way plug in harness bc I believe my wires are different in my 2001 chevy 1500 LS silverado. Bc on the panel, the upper right prong has power when the key is turned on amd no others have power when the key is off. The bottom left prong is for when the brakes are applied amd I need to know what the other prongs go to to readjistthe wires on the plug for my brake controller... thanks

Jameson C.

10/1/2025

@Charles We aren't aware of there being any differences between your truck and the info and diagrams above. That said if you have your owners manual the information would be there if different. It also should be abbreviated and listed on the lid of the panel as well.

Charles

10/1/2025

@JamesonC I dont have the owners manual. Bought it from a private individual.

Jameson C.

10/1/2025

@Charles If you Google 2001 chevy silverado owners manual the first result looks to be the correct pdf file.

Jack S.

8/18/2025

I bought my 2003 Sierra 1500HD with a Reese Brakeman Compact controller already installed, it is plugged into the junction box by the brake pedal. My cruise control quit working when I unplugged it. I installed a new Tekonsha Brakeman IV, and the cruise still doesn't work. Cruise only works with the old Reese plugged in. I verified that the wiring is the same on both controllers. Any ideas on what to look for?

Jerred H.

8/19/2025

@JackS That's a new one! I am leaning towards you having a bad brake controller that keeps tripping the brakes and kicking off your cruise control. What do you mean by junction box? The Tekonsha brake controllers have a plug in adapter item # 3015-P. If you're using one of these it's a bad controller.

Jack S.

8/25/2025

@JerredH The junction box by the brake pedal, as mentioned multiple times in this write up. I just pointed that out to let you know it could only be installed the one way, and it wasn't spliced in, potentially in the wrong place, and nothing was modified. Since the cruise control doesn't work with either of the brake controllers unplugged, it must be something wrong with the pickup. It just doesn't make sense it only works perfectly fine with the old Reese plugged in. The Tekonsha controller works great for the trailer brakes, and functions as normal as I was hoping. I only upgraded from the old Reese because I didn't think it had a sync adjustment, and it kept locking up my trailer brakes. I found the sync adjustment on the side back behind the mounting tabs after removing it of course! I will just have to reinstall the old Reese since that's the only configuration that allows my cruise control to function until I figure something else out.

Steve R.

7/17/2025

I have a 2001 GMC Sierra SL 2WD with a factory 7 way trailer connector but does not have a trailer brake controller. I purchased a Tekonsha Prodigy ID and a Tekonsha 3025-S Brake Control Wiring Adapter for GM. I'm have issues with understanding the wiring between the two. if you read the adapter ( which plugs directly into the panel under the dash of my truck). After just plugging in the 3025-s adapter to the panel under the dash, be wired up to the controller color for color or is it different? I really don't want to fry anything here!

Nick S.

7/17/2025

@SteveR Hey Steve, the wiring should be color for color. It looks like on that harness the white wire is the ground, the black wire is the power wire, the blue wire is the brake power, and the red wire is break switch. On the actual controller it should be the same as well. If it has a plug you would need to cut that off and splice the 2 together. Since they are both Tekonsha, the colors should match.

Quentin

4/27/2025

I have a 2007 gmc sierra 2500 classic everything works at 7 pin connector except power to blue wire electric brakes. There is continuity.on blue wire from brake controller to the pin on plug but no voltage . Brake controller is good 40 amp fuse in stud one is good 30 amp fuse in stud 2 is good.

Jose C.

6/18/2023

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!

Mike L.

6/30/2023

@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.

3/28/2023

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

Mike L.

3/29/2023

@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!

Helpful Links

faq-cbc.aspx

Mike S.

3/29/2023

@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.

3/5/2023

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?

Mike L.

3/14/2023

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.

Helpful Links

faq-brake-control-troubleshooting.aspx

Ozzie V.

5/15/2022

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.

5/16/2022

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.

Helpful Links

faq-brake-control-troubleshooting.aspx

faq-installation-of-brake-controller-from-scratch.aspx

faq-wiring-7-way.aspx

question-54961.html

Anthony C.

4/26/2022

Hi there thanks for the helpful guide 1 question though, for the blue wire do I connect it to the stud on the fuse box? or do I just solder the white wire onto the blue wire and run the brake controller connection all the way to the back to Connect to my 7 pin connector without connecting the brake controller wire to the stud on my fuse box. Thank you

David B.

4/26/2022

What's up Anthony? You need to connect the white and the blue wires together, splice or solder, then you run it all the way back to the trailer brake circuit on the 7 way connector. If you have any more questions, I'll be here to help.

Helpful Links

question-6746.html

Anthony C.

4/26/2022

@DavidB Thanks a lot for the info!! Another question and my last one, regarding the red auxiliary wire. I need to connect the red wire to my 12 volt battery via a 30 amp circuit breaker and wire that red wire all the way back to my 7 pin connector as well? Thanks a lot man I really appreciate this. I have not been able to find any information about this

David B.

4/27/2022

Red is your brake signal. Black is the hot lead. Let me link you to a some different guides and a video I think will help you. If you need any more clarification please let me know, I'll be here.

Helpful Links

faq-etbc7.aspx

faq-installation-of-brake-controller-from-scratch.aspx

tv-demo_etbc7.aspx

See All (9) Replies to Anthony C. ∨

Kyle

2/27/2022

Really really need help! I’ve got the red wire hooked up but where do I Hook the blue wire up by fuse block??? 4792170745

Les D.

2/28/2022

Ok Kyle let's see what is going on here. First, what is the brand name and model number of your brake controller? Also, what is the year/make/model of the vehicle it is attached to. Typically, the black wire runs from the battery to the brake controller. The red wire runs from the brake pedal switch to the brake controller. The white wire attaches to a bare metal chassis ground near by, and the blue wire gets to the trailer brakes one way or the other. If your vehicle was wired for towing, there may be a blue wire connector near by.

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