Trailer brake controller wiring.

[CnM 59]

I'm trying to install an electric trailer brake controller and I'm looking for the "cold" side of the brake light switch. The blue wire terminates at the plug, the red wire seems to be hot all the time so that makes me think the black wire would be the cold side. Problem is when I step on the brake I don't get anything at the black wire.
Am I missing something here?
04 HR Imperial.
Thanks for your help,
Chris

[mccrob]

Your on the wrong track Monaco breaks the ground to trigger a relay that makes the brake light hot. You can find the brake wire in the electric bay under the drivers feet trouble is it will be hot when the exhaust brake is on overheating your trailer brakes on a long down grade. Search drfilm in the search box he has a diagram of how to wire it up

[BigLar368]

Originally Posted by mccrob

Your on the wrong track Monaco breaks the ground to trigger a relay that makes the brake light hot. You can find the brake wire in the electric bay under the drivers feet trouble is it will be hot when the exhaust brake is on overheating your trailer brakes on a long down grade. Search drfilm in the search box he has a diagram of how to wire it up

Bob is correct. I used a small relay to convert the ground to a hot wire signal. This can be done with any 12V, hot all the time wire. When the brake is used the hobbs switch connects the grounds. Use the dead side of the hobbs switch and when the brakes are used it send a ground signal to the extra relay completing the circuit and you now have 12V for the brake controller.

[Ivylog]

On my 04 Dynasty I gave up mounting the brake controller in the dash area because I never found the 4 spare wires at the back... not until a year later after mounting the brake controller in the back where you have everything you need, making for a simple installation. Once adjusted you rarely have to change the gain/voltage it puts out.

You can remove fuse #1(exh brake) on the board with 3 fuses in the center of the board in the front run box so your brake lights do not come on until you actually use your brakes

[CnM 59]

Originally Posted by BigLar368

Bob is correct. I used a small relay to convert the ground to a hot wire signal. This can be done with any 12V, hot all the time wire. When the brake is used the hobbs switch connects the grounds. Use the dead side of the hobbs switch and when the brakes are used it send a ground signal to the extra relay completing the circuit and you now have 12V for the brake controller.

Thank you BigLar, I understand what you are saying. Is the Hobbs switch you mention the one in my picture that's attached to the top of the brake cylinder?
Chris

[CnM 59]

So if I use this wiring diagram and think of the brake pedal switch as the horn button this should work correct? Do you think a 15 amp fuse will be sufficient?
Thank you all again for the help.
Chris

[BigLar368]

Originally Posted by CnM 59

So if I use this wiring diagram and think of the brake pedal switch as the horn button this should work correct? Do you think a 15 amp fuse will be sufficient?
Thank you all again for the help.
Chris Attachment 211709

The diagram you posted would work. The ground signal would come from the dead side of the Hobbs switch so when the brakes are depressed it would send a ground signal to the relay to transfer 12V positive to your controller. As for your original pic both of my Hobbs switches are two wire only and all the wires are black. You can get in there with a test light and have someone push the brakes to see what you have. You might get lucky and find a 12V positive switched off the Hobbs switch. I see three wires and one is red. All these RV's are different.

[CnM 59]

Originally Posted by BigLar368

The diagram you posted would work. The ground signal would come from the dead side of the Hobbs switch so when the brakes are depressed it would send a ground signal to the relay to transfer 12V positive to your controller. As for your original pic both of my Hobbs switches are two wire only and all the wires are black. You can get in there with a test light and have someone push the brakes to see what you have. You might get lucky and find a 12V positive switched off the Hobbs switch. I see three wires and one is red. All these RV's are different.

My red wire at the Hobbs switch seems to be always hot so I'm wondering if I can tap off of that to use as my positive to the relay. Use the ground signal from the black wire (dead side) to the relay. Sounds like how the system is wired for the brake lights. Lol. I'll get this figured out eventually. Think I should run a new positive or use the positive on the Hobbs switch?

[BigLar368]

I ran a new wire since there is a major fuse outlet in the compartment on the drivers side in front of the wheel. You can use fuse rider to tap into fuse panel.

[vito.a]

I ran the +12v from a "Spare" position in the front run bay. I ran the wire out the upper corner of the front run bay and over up through the floor next to the steering shaft.
The hardest part of this was running the trailer brake wire from the drivers area to the trailer hitch. It took us a long afternoon to run the wire up through the center of the chassis.

Trailer Brake Control Prewire? 2004 Signature http://www.irv2.com/forums/f115/trailer-brake-control-prewire-2004-signature-366077.html

[CnM 59]

Originally Posted by BigLar368

I ran a new wire since there is a major fuse outlet in the compartment on the drivers side in front of the wheel. You can use fuse rider to tap into fuse panel.

I ran a new positive wire from the fuse box and this is how I wired the relay. My problem is its backwards from what I need. Seems I have a ground at the Hobbs switch all the time until the pedal is depressed. Like Bob said in the beginning, Monaco breaks the ground to activate the lights. What do I need to change to make this work?
Thank you all.

[BigLar368]

The 85 Pin should only contact ground when you depress the brake pedal. Hook up your test light to a 12V source and check which wire is grounded coming from the hobbs switch when the brake is depressed. Basically 85 pin will be a dead wire until you depress the brake pedal sending a ground signal to the relay letting it close and make contact sending 12V.

[RVH.O.G.]

The signal wire that goes to the tail light, I ran to a 2 psi pressure switch on the treadle valve. That way it is impossible for the trailer to come on unless I am applying the service brake.

[Bob Prince]

Originally Posted by mccrob

Your on the wrong track Monaco breaks the ground to trigger a relay that makes the brake light hot. You can find the brake wire in the electric bay under the drivers feet trouble is it will be hot when the exhaust brake is on overheating your trailer brakes on a long down grade. Search drfilm in the search box he has a diagram of how to wire it up

I had a Brake controller installed when I purchased my coach a few months ago. We pull an enclosed trailer weighing approx. 7500-8000 lbs
We usually run engine brake on low all the time. I haven't noticed anything different than I do pulling with my pick up truck.
how do I know if the engine brake is setting of electric trailer brakes or is it at all?

P.S. this is our first DP so I am still leaning.
Thanks, Bob Prince