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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.

Questions and Comments about this Article

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

Etrailer Expert
Reply from 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.

Anthony C.

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

Etrailer Expert
Reply from David B.

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.

Reply from Anthony C.

@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

Etrailer Expert
Reply from David B.

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.

Reply from Anthony C.

@DavidB I installed the 7 pin connector however my truck now has a bit of a. Hard time starting. I had to turn it off then turn it back on because the car rpm would just die as soon as I started it, I would have to push on my accelerator to barely keep it alive it sounded like my engine was fluttering and it just kept on getting quieter. I decided to turn the truck off and disconnect my battery. My battery is rated at 650CCA it’s a $140 DieHard 78-0 battery. Would I need to upgrade to a new alternator and battery? My alternator looks like it’s 12+ years old. Thank you.

Etrailer Expert
Reply from David B.

Hey Anthony, can you tell me the make/model/year of your truck and what wire harness and controller you have installed. I'm thinking a wrong part might be an issue here. If you have an alternator that old it wouldn't hurt to get it checked out though. Let me know those items so we can get this figured out for you!

Reply from Anthony C.

@DavidB my truck is a 2002 Chevrolet Silverado 1500 Extended Cab 4.8L V8 , I installed part number hopkins 47185 it is a 4 pin to 7 pin connector. I wired a 10 gauge auxiliary wire to the cars battery and put a circuit breaker between the wire that extended from my battery to the 7 pin connector in the back of my truck. I have yet to buy a controller I am just trying to get the truck set up for a 7 pin it didn’t come with the tow package or the hitch or anything. I really appreciate you thanks alot!!!!!

Etrailer Expert
Reply from David B.

Okie dokie, some wire somewhere has been crossed or shorted out, I think it would be in your best interest to remove everything and start over. If you can get a brake controller now I suggest doing that so you can do the complete install at one time. If not that is OK and you can get the connector installed before hand. So starting over: White is ground, blue is brake, black is hot lead and the purple is auxiliary. What brake controllers are you looking at? Are you going to be towing a lot or just a little. I have a few different options for either and I can save you some more time depending on what you want to do.

Reply from Anthony C.

@DavidB I actually had another question, I fixed my previous issue. But how do I wire the reverse lights on my 7 pin? I just have the reverse light left to wire but am not sure where to run it to? Thank you so much

Etrailer Expert
Reply from David B.

That's great you figured it out! On a 7 pin the center pin will be the reverse light function... Let me link you to one of our expert answers that talks about this and offers a diagram for more clarity. If you need anything else come on back, I'll be here to help.

Kyle

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

Etrailer Expert
Reply from Les D.

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.

Jim M.

I just did this on my 1999 Chevy Silverado very helpful! I used a Draw Tite I Command from you guys my question is the lights stay on as if power to it is constant should I be worried about a dead battery?

Etrailer Expert
Reply from Les D.

@JimM, I suppose you mean that there is a light on the Draw-Tite brake controller? This is normal. After 15 minutes, or so, the controller goes into sleep mode. The power draw is minimal and would take months to cause a battery problem. If you were to put your Silverado into storage for months, you could pull the controllers plug.

Robert S.

Why isnt the brake controller working after pluggin it in to the electrical box as per instructions. I plugged in the wire harness in second plug and get nothing to brake controlller and the lights to the trailer. I used the wires above the spare time.

Etrailer Expert
Reply from Les D.

Which brand and model number brake controller are you referring to and what is the year/make/model of your vehicle. The first thing we will check is the truck fuses. Then we will measure voltage on the lines to and from the brake controller to make sure the BC is getting power, and if so, does it send voltage to the 7-way bumper connection.



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