7 Wire Brake Control Install

If you have the factory installed tow package there should be a pigtail in the glove box. The pigtail plugs into the electrical panel below the dash on the left side. If you didn't get the factory package you should buy an aftermarket pigtail.

Now if you want a real brake controller that works like the Ford unit, look here:

All other controllers work by just guessing what your foot is doing. Yes, I know they cost a lot, but there is no other way to get real control except buying a Ford. Many will tell you about their favorite controller, but they don't have a clue how they work.

The 2002 and later models didn't come with the pigtail, even if they were equipped for it. It's an item to be purchased from the dealer. If the OP doesn't already have a controller, Tekonsha's Prodigy is one of the leading models, and they offer a plug-and-play install with a harness purchased from them. Has the GM plug on one end and the Prodigy plug on the other. My father's used one for several years now, and is planning on upgrading to the new model.

is the site.

I've got two Z71s, '98 pickup and '00 Tahoe. Both had harnesses tie wrapped by the spare tire for trailer lights and brakes. Lights and ground are right behind the bumper in a single bundle. Two other heavy gauge wires (blue and orange) are on the driver side by the spare. Other ends of these wires are hidden behind the brake booster. Have several HD trucks in our company fleet that have the same setup. If your truck is equipped, a wiring diagram should be in your manual.

Yeah, you are all wired and ready to go. Does it have the "tow package" (factory hitch)?

You might have gotten a pigtail for connection to a controller. For some reason GMC didn't include it in the Sierra. You can buy them from GM.

If you are getting a whole new brake control you can order the harness at the same time.

I got my controller (Tekonsha Prodigy) at RJays

Also bought their ready made cable for connecting to GM products. Took about 10 minutes to install. Two sheet metal screws and plug it in.

The Tekonsha site has installation instructions:

My 2004 GMC 2500HD came with the pigtail for the brake controller.

Interesting. Did you get the fuse for the 12 volts too? From what I heard there should be a fuse along with the controller cable.

I ordered it with the 5th wheel pigtail too. Got the plug wired and no 12 volts. Then discovered the plastic plug in the fuse slot. Had to pay something like $3.50 for a fuse.

Everyone, Thanks a ton! There was a wiring harness in the glove box and I'm investigating the rest. Yes, my truck was ordered with the tow package. It at least looks like Chevy and the brakes control companies are starting to get it together.

My 01 Chevy was ok but didn't have a fused 12v line for the RV or a plug to connect into the brake line. Looks like my 04 is a step better. Very nice to see. Now if they would just include that with the towing package. Oh well, maybe in 2010. Can't move too fast.

Lynn, Very interesting. I am an electrical engineer by trade (please don't hold that against me). I wasn't really sure how the electronics worked but knew that it was NOT actively coupled to the pressure on the brake pedal. The new system by Brakesmart looks/sounds pretty cool. However I'm a weekend warrior RV person. I tow maybe 10 - 15 times a year. If I could have ordered this unit installed from the factory I would have. However the $350 price tag and installation are more than I really want to get into. I've had Tekonsha units for the last three trucks (91, 96,

01). I'm not very impressed with they way they work but they get the job done for relatively little $. I'll most likely stay with them for at least one more truck. With any luck Chevy (or maybe Dodge) will adopt the concept of adding brake control units at the factory. If that happens I hope they go with this system. Thanks for all the info!

Me too but they don't cover electronic brakes in Circuits 301. At least they didn't in the "olden days".

I wasn't really sure how the electronics worked

A couple more points. Did they include a fuse?

Under the hood directly in front of the driver is a fuse/relay box. Auxiliary #1 is your 12 volt supply and Auxiliary #2 is the Brake. Put a 30 amp fuse or resettable circuit breaker in #1 and a 20 amp fuse or breaker in #2.

The owners manual about Aux. 2 confused me for a bit. It says something about not using a fuse if there are two batteries. I have two batteries (Duramax Engine). Reading a bit more I realize they were talking about an option for two batteries with a gas engine.

In mine there was a dummy plastic plug that looked like a fuse in Aux. 1.

Hi Rich, No, brake control units weren't covered in my classes either ;-)

Thanks for the extra info on the fuse box and such. I haven't yet dug in to do the full install yet because I decided to get a new controller instead of taking my old one out of my 01. The link Lynn supplied and the information there made me read up a little. I decided to upgrade my controller and so I ordered a new one. I'm hoping it is here before the weekend so that I can install it then.

I read another news group on a GM page and they also had a bunch of posts on this subject. You are correct that there was a "dual" battery option for gas trucks that allowed us to carry and charge an extra battery. I so wished my truck had this option since I'm an RV guy. I would use this to swap out batteries on my camper and I could charge one while driving around without the camper. Anyway you mentioned that you had the dmax. Your setup is different than mine. This is explained in more detail on the other groups page.

For anyone interested in this more check out this link

I hope this link works.

If my controller comes in Friday I'll have more details on my install on Monday.

Thanks for the support/help!

I looked at the posts on that forum. I note that one guy misread the insturctions as I did at first, saying that the instructions are not to install at fuse. That is true only if you have the dual battery option. The Dmax wire is essentially the same as all the other vehicles except the two starting batteries are wired in parallel.

I noted that one fellow had the same problem I did. He saw the plastic plug in #1 slot., with a label on it and thought it was a fuse.

I expect you will find that #1 is power for the trailer and #2 is for the brake control.

Someone else said that Stud #1 was for DMax electronics. That is not true either. As I said mine came with a plastic plug just like the gas engines.

Thanks again for the additional comments. My brake control unit didn't come in Friday or Sat so now it will be next weekend before I get a chance to play with it. The company I ordered it from is really so on shipping.