Wiring help needed - Unified Tow Brake on W-24

[RV 4 2]

Figuring that pros take 1-2 days to install a tow bar/braking system on a coach and toad, I worked all weekend (4+ days now) to put in a Unified tow brake (+tow bar...) on the coach and Saturn Vue. I ran into three issues on the coach side that I need help on.
In trying to connect up the tow brake controller to the brake switch I see 3 wires on what I think is the proper switch to get the signal from. The switch has a white, orange and light blue wires coming out of it. Orange is always hot. Lt blue and white are only hot when pressing on the brake pedal. Since I don't want to play the cut and splice game on the wrong wire, which wire should I be using? The white or lt blue one?
#2 - Also, for those who know better than I, when using the test light on the 7 pin connector at the back of the coach, shouldn't the blue trailer brake signal provide some voltage at the pin when the ingnition is on and the brakes are pressed? All I get when the ignition is on and the brake pedal is pressed are the 12+V, right and left tail lights showing voltage with a test light. The 12+V is hot upon ingnition on.
#3 - From the US Gear wiring harness, the lt blue wire coming out is the supply signal wire for the trailer tow brakes. This would be the same wire as the blue one on the 7 pin connector. I was going to tap into that under the dashboard since the coach is already wired but I cannot find the wire anywhere. I would prefer to do this instead of running a new wire. Does anyone know where the source of this wire is located under the dash?
Any help would be greatly appreciated.

[RV 4 2]

Figuring that pros take 1-2 days to install a tow bar/braking system on a coach and toad, I worked all weekend (4+ days now) to put in a Unified tow brake (+tow bar...) on the coach and Saturn Vue. I ran into three issues on the coach side that I need help on.
In trying to connect up the tow brake controller to the brake switch I see 3 wires on what I think is the proper switch to get the signal from. The switch has a white, orange and light blue wires coming out of it. Orange is always hot. Lt blue and white are only hot when pressing on the brake pedal. Since I don't want to play the cut and splice game on the wrong wire, which wire should I be using? The white or lt blue one?
#2 - Also, for those who know better than I, when using the test light on the 7 pin connector at the back of the coach, shouldn't the blue trailer brake signal provide some voltage at the pin when the ingnition is on and the brakes are pressed? All I get when the ignition is on and the brake pedal is pressed are the 12+V, right and left tail lights showing voltage with a test light. The 12+V is hot upon ingnition on.
#3 - From the US Gear wiring harness, the lt blue wire coming out is the supply signal wire for the trailer tow brakes. This would be the same wire as the blue one on the 7 pin connector. I was going to tap into that under the dashboard since the coach is already wired but I cannot find the wire anywhere. I would prefer to do this instead of running a new wire. Does anyone know where the source of this wire is located under the dash?
Any help would be greatly appreciated.

[oemtech]

I did this on my 04 Mountain Aire... I need to crawl under the dash to look at which wire I used. OBTW - You MUST install the blocking diode in the brake circuit.

I will check and post the results later.

[RV 4 2]

Dale, Yea, I know about the blocking diode. It is sitting right next to the brake pedal.
Thank you for taking a look for me.

[oemtech]

This going to cost you...

Here is the brake hookup.


I made my own cable from the controller to the toad. This photo shows the blue wire (inside the cable cover) and the power wire to charge the battery.


If you go to Dales RV Tips in my signature and look at RV Tow brake you can see all the USG install photos.

On edit:

The black wire is actually an extension of the "Orange" wire described in the install instructions. Remember, my unit was used so all the control wires were cut. But, the previous owner labeled them and where they got attached.

Here is part of the instructions that I used to find the correct wire. I was lucky I hit it on the first try.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">GASOLINE CHASSIS: You may have more than one wire that reacts "cold/hot". Once you have found the wire(s) that react this way, we then must identify the one which controls the brake lights on the back of the motor home. The only way to do this, other than contacting your chassis manufacturer to see if they can tell you which wire, is to cut a "cold/hot" wire and apply the brake pedal and see if the brake lights on the rear of the motor home is dead. If so, this is the correct wire. If the brake lights are still working, then the wire you cut is not the correct wire that controls the brake lights and must be re-connected and then proceed to cut another wire that is "cold/hot" and again check to see if the brake lights are off or not until you have correctly identified the brake light wire (NOTE: The reason you may find multiple wires that are "cold/hot" is because of other accessories utilizing the brake light switch. Such as the cruise control, torque converter lock-up, ABS, etc.). </div></BLOCKQUOTE>

[RV 4 2]

Dale, Thank you for the pictures. And Yea, I am sure it is going to cost me dearly somewhere along the line.
This brought up more questions. I sent you a PM.

Thank you.

BTW, your DIY site is awesome. Great ideas and improvements. You have gotten my brain working for improvements on my coach as soon as the list gets small enough, I have ideas for more things.

[RVJeeper]

Dale - Assume this would be the same wire (blue) that I'd tap into for my trailer brake controller?

[oemtech]

Ron,

Without looking at your install instructions I wouldn't assume anything.

[RV 4 2]

Dale, on your edit, I read that part of the USG instructions and already went through that cut-test-reconnect-cut again-test... on my toad and I didn't want to do it with the coach. That was why I posted this for questions. It is bad enough we have to splice at all. I think it would be nice if MH manufacturers would provide a small standard towing fuse block under the dash or.. better yet, a common connector in which to plug a pigtail were we can tap off this stuff without splicing. My ford truck had it when I put in the prodigy brake controller. I just bought the right pigtail made by Tekonsha to plug in between the Ford harness and the brake controller. I know, a bit too much to ask.

[oemtech]

I know what I am about to tell is a day $ short... But, if you go to a good to a good electronics store you can get a "plug" pin removal tool. It slides over the pin and compresses the little barbs that hold the pin in the plug. They have different sizes - to fit the male or female pins.

[RVJeeper]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by oemtech:
Ron,
Without looking at your install instructions I wouldn't assume anything. </div></BLOCKQUOTE>

Dale - Same as Mike installed on his Ford: the Tekonsha Prodigy. The wiring instructions call for one of the wires to be connected to the brake light wire near the brake pedal. Assuming that the blue wire mentioned would serve that purpose? BTW I share Mike's sentiment that it would be much easier if Workhorse would include the trailer brake connector plug. We had one on our old Coachmen Class C (on the Ford chassis) and installed the brake controller in about 15 minutes!

[oemtech]

Your preaching to the choir...

[RVJeeper]

One can always hope that someone from management is listening in!

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by RVJeeper:
One can always hope that someone from management is listening in! </div></BLOCKQUOTE>Ford has always had a "BLUE" wire back to the trailer harness on all the vehicles I've owned in fact a modular connector with pigtails came with my 1993 Château and my 1997 F250 so I could mount and plug in a brake controller.

As best as I know GM doesn't provide an OEM solution for brake controllers in their harness therefore it's basically not a Workhorse thing. A dedicated brake controller wire for the most part on motorhomes is largely unused however it could be quite useful for applications other than a brake controller.