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Discussion Starter #1
Hello everyone. I have just purchased a new travel trailer and had to update my wiring harness to accomidate the trailer brakes. I had no problem because the hitch was factory installed and the wiring harness was easily accessible. The problem is that I can't figure out where exactly the wires are, coming off the brake control switch. From what I've read the switch and wires should be under the dash and close proximity to the brake pedal. If anyone out there could help me out here I would be extremely appreciative. Thanks Trin
 

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Discussion Starter #3 (Edited)
1999 Suburban brake control switch location?

Hi! Thanks for the diagram. I can wire the new controller without any problem however, the brake control switch is not located on the back of my brake pedal. That is what I'm having trouble with. I can't seem to find the switch or the wires. Are they crammed up somewhere in the dash that I can't easily see them?
Thanks Trin
 

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The switch on my 94 is right behind the brake pedal. Not sure if it’s the same on the 99, but it doesn’t look like the old style switch.

It’s a large white block attached to the brake rod.
 

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Pictures gotta love 'em

There were a couple of different types used they look like this:
 

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Discussion Starter #6
1999 Suburban Brake switch

Thanks Guys. The pics really helped and I finally found it. It sits on top of the brake shaft and is not easily accessible at all. Do you have any tips on how to get it off? It looks as if it has a round washer on the side thats holding it on. I only need to get to the wiring to splice in the harness from the new brake controller.
 

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I just looked at mine and it has a red, white, orange, and purple wire coming out of it. On the top plug.

I would not take the switch out, try to get at the wire you need from the plug.

Now there is all the help I can give you unless some one else has a diagram of the wiring harness for your vehicle.

Sorry I can’t be of more help.
 

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Discussion Starter #8
1999 Suburban Brake Controller wiring harness update

Okay- I finally got it wired. I called the manufacturer of the brake controller and it seems that since I have a factory installed hitch that the wiring harness was easily accessable. I didn't need to mess with the brake switch at all.
At the back of the truck is a seperate set of wires, One blue (for the trailer brakes) and one orange (for auxillary power) for the battery on the trailer.
Under the dash, next to the emergency brake is a black conveniance box. At the bottom of the box is the letters GRN, next to that is the letters NAT with a small recessed box with two male spade connectors. The spade on the right goes to the brake switch. The wire from the brake controller is terminated there. Under the hood, up against the firewall is the termination end of the orange and blue wires from the wire harness that gets fed back under the dash into the brake controller. I spliced a wire into the orange line under the hood for the auxillary power. On the drivers side, near the fire wall is a black fuse box. At the front of the fuse box (closest to the firewall) are two hot terminals posts. This is where the orange wire for the auxillary power gets terminated.

Hopefully this will help someone else not to go through what I did to put in a brake controller.

I also want to thank everyone who tried to help me on this little venture.

Trin
 

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Thanks Trin,

I have the same set of wires in mine so now I will know how they go when I need to hook them up.
 

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Discussion Starter #10
1999 Suburban brake controller wiring

Glad I could help Gary. These forum boards are a godsend for help in repairs. I know they've saved my butt a couple of times. I took the trailer out this weekend and went camping. The brake controller worked like a charm.
 

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Cudos

Thanks TD. It is contributions from folks like you that make these forums worthwhile.:great:
 

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Their are two wires you need to find and they are under the brake master cyclinder mounted on the firewall. One is orange and the other is blue and if you can stand on your head and look around corners with your eye you will see them. The blue wire goes to your brake control and the orange wire is an Auxiliary 12 volt to the trailer. The other hard part is finding the brake light wire to control the electronic brake control. Under the dash below the steering column is a connector with a white wire at one end, if you use a meter or a test light you can find the wire an that will connect to the brake control to activate the trailer brakes. Hope this helps this is where I found my info and I'm sure that info is still on the site somewere.
 

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Okay- I finally got it wired. I called the manufacturer of the brake controller and it seems that since I have a factory installed hitch that the wiring harness was easily accessable. I didn't need to mess with the brake switch at all.
At the back of the truck is a seperate set of wires, One blue (for the trailer brakes) and one orange (for auxillary power) for the battery on the trailer.
Under the dash, next to the emergency brake is a black conveniance box. At the bottom of the box is the letters GRN, next to that is the letters NAT with a small recessed box with two male spade connectors. The spade on the right goes to the brake switch. The wire from the brake controller is terminated there. Under the hood, up against the firewall is the termination end of the orange and blue wires from the wire harness that gets fed back under the dash into the brake controller. I spliced a wire into the orange line under the hood for the auxillary power. On the drivers side, near the fire wall is a black fuse box. At the front of the fuse box (closest to the firewall) are two hot terminals posts. This is where the orange wire for the auxillary power gets terminated.

Hopefully this will help someone else not to go through what I did to put in a brake controller.

I also want to thank everyone who tried to help me on this little venture.

Trin
I got SO excited when I read this post. I had been trying the stand-on-my-head-and-see-around-corners method and couldn't figure out the brake switch. (I'm used to wiring motorcycles where everything is within a few inches of the surface.) I went back out to the truck, excited to connect to the NAT lead because I knew I had seen that in the "convenience" box, only to find that mine doesn't have any connections there, just the empty holes labeled "NAT."

1995 Suburban C1500, by the way, with the full tow package (I checked every one of the codes in the glove box; I have every tow option available for this truck).

CAN SOMEONE PLEASE EXPLAIN TO ME WHY TRUCKS WITH TOW PACKAGES DON'T HAVE BRAKE CONTROLLERS?!?! For decades people have been using aftermarket hacks to imperfectly control the brakes on their trailers when the truck manufacturers could have made the truck to control it naturally. This irritates me to no end.


- Jon
 

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I got SO excited when I read this post. I had been trying the stand-on-my-head-and-see-around-corners method and couldn't figure out the brake switch. (I'm used to wiring motorcycles where everything is within a few inches of the surface.) I went back out to the truck, excited to connect to the NAT lead because I knew I had seen that in the "convenience" box, only to find that mine doesn't have any connections there, just the empty holes labeled "NAT."

1995 Suburban C1500, by the way, with the full tow package (I checked every one of the codes in the glove box; I have every tow option available for this truck).

CAN SOMEONE PLEASE EXPLAIN TO ME WHY TRUCKS WITH TOW PACKAGES DON'T HAVE BRAKE CONTROLLERS?!?! For decades people have been using aftermarket hacks to imperfectly control the brakes on their trailers when the truck manufacturers could have made the truck to control it naturally. This irritates me to no end.


- Jon
Jon,

The newer trucks have the connector. It's not rocket science, it's just a couple of extra wires you need to run from the dash to the rear of the truck. If you don't feel comfortable doing this take it to U-Haul and they can do it for you.
 

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No, it's not rocket science. And I've done MUCH more complicated work. What irritates me is that the truck manufacturers could build in an intelligent controller that integrates with the actual truck braking system. Instead we have to do imperfect aftermarket options which attempt to time the braking with the brake light (highly flawed), base it on a pendulum which reacts to both gravity and inertia (fails on inclines and declines), use an inertia-based system which is able to compensate for changes in gravitational pull for inclines and declines (at the expense of sensitivity), or a system which taps into the hydraulic brake system to measure the pressure in the line (which method, like an electrical multimeter, influences the reading and is therefore imperfect though the best of these systems, while also the most complicated to install and the manufacturers of these systems warn that it can reduce truck braking power if your hydraulic system has insufficient capacity to handle the brakes and gauge).

When even an aftermarket option costs $50 to $200 (parts only) at retail, the cost for a vehicle manufacturer to include this in the design of the vehicle and provide a superior solution would be even less. (Consider the economies of scale, and the efficiency of assembly-line production.)

Consider also that this would not preclude the existence of aftermarket options, as you could always go with an upgraded or alternative solution if you so desire. Meanwhile countless truck buyers would be better served with turnkey towing solutions that keep themselves and others on the road safer.


The U-Haul store will install it IF you have the wire loom ready under the dash. If not they won't touch it. At least not at my local stores. They will refer you to a full-service mechanic to route anything through the firewall, for instance. At least in my experience that's the case.

I've rebuilt engines, restored entire motorcycles from the ground-up, as well as customizing bikes. In the biking world there's a saying that it's not a custom until you've cut something off or welded something on. Again, this isn't that involved, I'm just annoyed that a vehicle with a tow package doesn't have even a jack ready for the controller much less the controller itself. It's a prime example of Detroit business practices that lead consumers to look elsewhere.


- Jon
 
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