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Brake signal for trailer brake controller


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Hi everyone, I need a little help figuring out how to get a brake signal for a trailer brake controller. I've searched and read all of the threads on here about this topic, but I'm still a little confused. I've found 2 brake wires that come out of my Monaco #2 box, 1 is grounded all the time until brakes are pressed then it turns into an open connection. The other is 12vdc until brakes are pressed then it opens.

After reading other threads and learning how Monaco used a negative switched ground to control the brake lights, I expected to find the negative wire coming out of the Monaco #2 box to be in a normal open status and close ( go to ground) when brakes are pressed. If that would have been the case, it would have made hooking up a negative triggered relay a simple process. To make things even more confusing is the previous owner installed a United Tow Brake Controller and some of the wiring for that is still in place. In my initial testing and snooping around my front electrical bay, I've unhooked the rectifier the UTB had hooked up and tried to focus on just the OEM Monaco system. I want to remove all the UTB stuff and start from scratch.

I'm familiar with wiring up a relay, but the way my brake signal currently is (normal closed negative wire), I'm confused how I would wire up a relay.  In this diagram of a negative triggered relay, the negative wire is the trigger and needs to close in order to send a 12v signal to the device (which would be my trailer brake controller). What am I missing? Thanks for any help!

 

 

PXL_20230914_143658082.thumb.jpg.a3409a365899a95a48406469ce2b1496.jpg

Edited by Pudgy Camper
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@Dr4film might be able to help, I know he put a controller on his 2002 Windsor.  He sent me some info on how he did it but since I've never did the install I'm not going to pretend what you might need.

Edited by jacwjames
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Unless Richard did it another way.  TWO ways... BUT, you need to verify (and I will not assume that you tested with the ignition switch ON...but you need to). .You need to find a 12 VDC from the Ignition.  Then put it on terminal 85 and put the Ground Signal (always ON) from the relay to terminal 86.  SO, when the brakes are pushed....the relay (which would be energized) will open up.  Then you feed the SAME 12 VDC from the Terminal 85 to the number 30 terminal.  THEN, your POSITIVE signal from 87A will be the signal to the brake controller.  NOW....remember, your controller is going to send out a high current signal.... What you are after is just the BRAKE PEDAL signal.  See the wiring from Etrailer...it is typical for a 4 wire brake controller.  The POWER (Black) wire has to have a 20 amp circuit breaker....from the Chassis STUD....NOT an ignition controlled source.  So, the Red or the brake is just a low amperage "controller.

https://www.etrailer.com/question-6890.html

When you turn on the engine...the relay is closed...as you have the ALWAYS ON ground from the Monaco relay....and then the Ignition ON 12 VDC positive.  SO, instantly....the relay closes.  THAT kills the circuit from 30 (Ignition ON 12 VDC) and 87A has NO signal.   Therefore you have NO power from 87A.  BUT, when you tap the brakes....then the relay opens or is de-energized... 87A is now HOT....as in your brake controller gets a "Brake Pedal" signal....

NOW....we have had some issues lately with brake lights and such.  SO....following your comment... MY POST ABOVE might not work....as in, we don't KNOW the source of the NEGATIVE GROUND signal.  If it is coming from the ECM, then you need a DIODE.  BUT the polarity is tricky.  You need to find a 3AMP 12 VDC diode.  NOW here is what you do.  NAPA sells them or you can order one.  The Negative is the CATHODE.  The Positive is the ANODE.  If you look at the DIODE, there is a an ARROW or triangle.  Hook up the GROUND (always ON) from the Monaco relay to the NEGATIVE SIDE.  Hook up the POSITIVE side of the diode to pin 86.  Thus, you have a diode in the circuit so there is NO chance of a feedback to the ECM.  YES, that will work.

OK...but if you want the easier way....then use the POSITIVE.  If I understand you.  There is a POSITVE coming out of the relay.  When you tap the brakes (assuming you are testing with the IGNITION ON....your TEST always has to be with the IGNITION ON)....then the positive drops out... the relay closes....and then 30 and 87A are closed.  SO...do the reverse of above.  Ground OUT 86.  Use the Positive, always ON, until Brakes are TAPPED, positive to the coil.  Same deal.  The relay is always ENERGIZED....but when you use the brakes, the relay De-Energizes....when it does, then the Ignition ON wire (fed to 30) is connected to 87A.  That goes to the RED in the 5 wire drawing....That is the same a BRAKE LIGHT.  I would not sweat or use the diode here.

That's how it works.  A word of caution.  Never yank out something that is not needed as long as it is working and all is well.  We have had folks cut out what looked like a redundant item.  OPPS....They do NOT know what was being used from what.  NOW....  I can't figure out, from you narrative why there was a DIODE in the UTB circuit.  I KNOW THAT.  Hooked it UP TWICE in two different motor homes. 

NOW, if there was a FUNCTIONAL UTB in your MH, then SOMEBODY had to run a wire back from the FRONT to the REAR (a LONG WAY and the hardest part of this).  IF they ran the wire back there and it was a #12, FIND IT.  Then you can use it for the BLUE...or the output to the brakes.  MOST of the brake controllers send out a variable voltage.  So, when you slam on the brakes...a FULL 12 VDC hits the brakes.  BUT, if you only #14 wire, yes...it is rated for 15 A, but you get a lot of drop from front to rear.  That is why you need a #12. 

NOW, check with your controller tech support.  Ask them if they have one or find one that requires a REAR Relay....where you put in 12 VDC and the relay will chatter..  Maybe be off the wall...but the hardest part is running the extra line.  I would NOT do that until I found the INFAMOUS blue wire that the UTB used. 
Scroll to the end....look at the wiring.  Figure out WHERE the infamous BLUE wire, that HAD to be run to the rear is.  Check it's size.  if #12, you have lucked out and saved yourself 90% of the install....Good Luck.

http://www.usgear.cc/utb_install/utb_install.htm

 

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14 minutes ago, Tom Cherry said:

Unless Richard did it another way.  TWO ways... BUT, you need to verify (and I will not assume that you tested with the ignition switch ON...but you need to). .You need to find a 12 VDC from the Ignition.  Then put it on terminal 85 and put the Ground Signal (always ON) from the relay to terminal 86.  SO, when the brakes are pushed....the relay (which would be energized) will open up.  Then you feed the SAME 12 VDC from the Terminal 85 to the number 30 terminal.  THEN, your POSITIVE signal from 87A will be the signal to the brake controller.  NOW....remember, your controller is going to send out a high current signal.... What you are after is just the BRAKE PEDAL signal.  See the wiring from Etrailer...it is typical for a 4 wire brake controller.  The POWER (Black) wire has to have a 20 amp circuit breaker....from the Chassis STUD....NOT an ignition controlled source.  So, the Red or the brake is just a low amperage "controller.

https://www.etrailer.com/question-6890.html

When you turn on the engine...the relay is closed...as you have the ALWAYS ON ground from the Monaco relay....and then the Ignition ON 12 VDC positive.  SO, instantly....the relay closes.  THAT kills the circuit from 30 (Ignition ON 12 VDC) and 87A has NO signal.   Therefore you have NO power from 87A.  BUT, when you tap the brakes....then the relay opens or is de-energized... 87A is now HOT....as in your brake controller gets a "Brake Pedal" signal....

NOW....we have had some issues lately with brake lights and such.  SO....following your comment... MY POST ABOVE might not work....as in, we don't KNOW the source of the NEGATIVE GROUND signal.  If it is coming from the ECM, then you need a DIODE.  BUT the polarity is tricky.  You need to find a 3AMP 12 VDC diode.  NOW here is what you do.  NAPA sells them or you can order one.  The Negative is the CATHODE.  The Positive is the ANODE.  If you look at the DIODE, there is a an ARROW or triangle.  Hook up the GROUND (always ON) from the Monaco relay to the NEGATIVE SIDE.  Hook up the POSITIVE side of the diode to pin 86.  Thus, you have a diode in the circuit so there is NO chance of a feedback to the ECM.  YES, that will work.

OK...but if you want the easier way....then use the POSITIVE.  If I understand you.  There is a POSITVE coming out of the relay.  When you tap the brakes (assuming you are testing with the IGNITION ON....your TEST always has to be with the IGNITION ON)....then the positive drops out... the relay closes....and then 30 and 87A are closed.  SO...do the reverse of above.  Ground OUT 86.  Use the Positive, always ON, until Brakes are TAPPED, positive to the coil.  Same deal.  The relay is always ENERGIZED....but when you use the brakes, the relay De-Energizes....when it does, then the Ignition ON wire (fed to 30) is connected to 87A.  That goes to the RED in the 5 wire drawing....That is the same a BRAKE LIGHT.  I would not sweat or use the diode here.

That's how it works.  A word of caution.  Never yank out something that is not needed as long as it is working and all is well.  We have had folks cut out what looked like a redundant item.  OPPS....They do NOT know what was being used from what.  NOW....  I can't figure out, from you narrative why there was a DIODE in the UTB circuit.  I KNOW THAT.  Hooked it UP TWICE in two different motor homes. 

NOW, if there was a FUNCTIONAL UTB in your MH, then SOMEBODY had to run a wire back from the FRONT to the REAR (a LONG WAY and the hardest part of this).  IF they ran the wire back there and it was a #12, FIND IT.  Then you can use it for the BLUE...or the output to the brakes.  MOST of the brake controllers send out a variable voltage.  So, when you slam on the brakes...a FULL 12 VDC hits the brakes.  BUT, if you only #14 wire, yes...it is rated for 15 A, but you get a lot of drop from front to rear.  That is why you need a #12. 

NOW, check with your controller tech support.  Ask them if they have one or find one that requires a REAR Relay....where you put in 12 VDC and the relay will chatter..  Maybe be off the wall...but the hardest part is running the extra line.  I would NOT do that until I found the INFAMOUS blue wire that the UTB used. 
Scroll to the end....look at the wiring.  Figure out WHERE the infamous BLUE wire, that HAD to be run to the rear is.  Check it's size.  if #12, you have lucked out and saved yourself 90% of the install....Good Luck.

http://www.usgear.cc/utb_install/utb_install.htm

 

Thanks Tom, I considered using the 87A terminal and using it as an normally closed relay, buy I was confused with all of the other threads talking about using term 87 and tying into the negative switched wire. I've tested my system both with the key on and off. The brake lights activate with key off as well as on. Running a blue wire from front to back shouldn't be too bad, being that I have a conduit system installed, just need to get the positive brake signal wire squared away.

The existing UTB wiring in my coach does have 2 wires that run to the back, but the previous owner ran them under the belly of the coach and some of the fasteners have already come loose and the wires are hanging pretty low under there. So my plan is to abandon all of the old UTB wiring and start from scratch with all new wiring for a standard trailer brake controller. Down the road I'll work on setting up a brake system for a tow vehicle, but I just want to get trailer brakes for now.

Also, thanks for the info on the 20amp circuit breaker and diode. If I go with the 87A option, I will go the simple route and use the always positive coming from my Monaco #2 box. I've seen the breaker in wiring diagrams, but was unsure why one was needed. There is actually one in the FR bay that was used with the UTB system.

Thanks again for your help!

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Jason,

Your Monaco #2 Box should have two connectors. The one you want is the right side Grey connector. It should be an 8 wire connector with only 6 wires on it. See photos. The white wires should be labeled. You can see from one photo which wire I tapped into with the blue wire tap.

Unless the 04 Windsor is different than the 02 that wire should be labeled Brake Signal. However, it is a negative signal wire and the brake controller needs a positive brake signal to work correctly. That's why the need for an 87 relay is to change the Monaco negative brake signal into a positive one.

Monaco #2 Gray Plug-01.jpg

Monaco #2 Gray Plug-02.jpg

Prodigy Brake Relay-01.JPG

Prodigy Brake Relay-02.JPG

Prodigy Brake Relay-03.JPG

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1 hour ago, Dr4Film said:

Jason,

Your Monaco #2 Box should have two connectors. The one you want is the right side Grey connector. It should be an 8 wire connector with only 6 wires on it. See photos. The white wires should be labeled. You can see from one photo which wire I tapped into with the blue wire tap.

Unless the 04 Windsor is different than the 02 that wire should be labeled Brake Signal. However, it is a negative signal wire and the brake controller needs a positive brake signal to work correctly. That's why the need for an 87 relay is to change the Monaco negative brake signal into a positive one.

Monaco #2 Gray Plug-01.jpg

Monaco #2 Gray Plug-02.jpg

Prodigy Brake Relay-01.JPG

Prodigy Brake Relay-02.JPG

Prodigy Brake Relay-03.JPG

Thanks Richard, they must have changed some things on the 04. After searching and reading old posts on this topic I expected to be able to do what you and others have done here and install a negative tripped relay like your pictures show. I found the wire in your picture that you have the blue suitcase connector on. However, on mine it's labeled 'brake lamp' #155b and is 12v hot until the brake is pressed. The wire to the right of it is the 'Brake Sig' #102 wire and is negative (grounded) all the time until the brakes are pressed then it opens.

Richard, when you refer to the signal wire as being a negative signal wire, is it a normally open negative on you coach? Meaning when brakes are pressed that wire goes to ground? If that's the case, mine is the exact opposite and it's grounded all the time until brakes are pressed then it opens. That's why I'm thinking I may need to use the 87A terminal on the relay, turning the relay into a normally closed relay.

Edited by Pudgy Camper
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Jason, Wire #102 rings a bell which does happen to be your brake signal wire.

Unfortunately, I no longer own the coach and it was back in 09 when I installed the brake controller. I believe that wire was open, then when I pressed on the brake pedal it closed and went to negative. Since the Prodigy brake controller needed a positive signal, I installed the relay between the Monaco Box #2 and the controller as described by the Unified Tow Brake PDF file attached.

I wired it such that when the white wire #102 received a negative signal it closed the relay which allowed a 12 VDC hot wire to flow to the brake controller.

I am not sure how you would wire a relay when your #102 wire has a constant signal all the time until you stepped on the brake and then it opens.

Possibly someone with more electrical knowledge than me will chime in to help you.

4 Pole Relay.png

Unified Tow Brake Controller Brake Signal.pdf

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43 minutes ago, Dr4Film said:

Jason, Wire #102 rings a bell which does happen to be your brake signal wire.

Unfortunately, I no longer own the coach and it was back in 09 when I installed the brake controller. I believe that wire was open, then when I pressed on the brake pedal it closed and went to negative. Since the Prodigy brake controller needed a positive signal, I installed the relay between the Monaco Box #2 and the controller as described by the Unified Tow Brake PDF file attached.

I wired it such that when the white wire #102 received a negative signal it closed the relay which allowed a 12 VDC hot wire to flow to the brake controller.

I am not sure how you would wire a relay when your #102 wire has a constant signal all the time until you stepped on the brake and then it opens.

Possibly someone with more electrical knowledge than me will chime in to help you.

4 Pole Relay.png

Unified Tow Brake Controller Brake Signal.pdf 174.62 kB · 0 downloads

Thanks Richard, I believe I can use the constant 12v wire and utilize the 87A terminal of a 5 pin relay. So that when 12v power is removed from the relay, it sends 12v to pin 87A which would be the brake signal for my trailer brake controller. I'm going to spend some time looking things over and test everything again just to make sure I'm not missing something!

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Jason, that would mean that the relay would be energized ALL the time unless you are using the brake pedal. To me, I would think that would cause the relay to fail prematurely being ON all the time. I don't know how reliable those relays are being powered all the time.

What say you?

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14 minutes ago, Dr4Film said:

Jason, that would mean that the relay would be energized ALL the time unless you are using the brake pedal. To me, I would think that would cause the relay to fail prematurely being ON all the time. I don't know how reliable those relays are being powered all the time.

What say you?

Yep the relay would be energized all the time until brakes were applied then it would just transfer the power over to a different pin, similar to hi/low beams on an automobile. I'm going to see if I can find a signal up on the firewall at the brake switch before I go that route. Also, my coach had a United Tow Brake Controller installed at one time and some of the wiring is still there but it's not wired like the UTB diagram shows, no relay anywhere. But I may revisit the wiring and see if there's something I'm missing.

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4 hours ago, Pudgy Camper said:

Yep the relay would be energized all the time until brakes were applied then it would just transfer the power over to a different pin, similar to hi/low beams on an automobile. I'm going to see if I can find a signal up on the firewall at the brake switch before I go that route. Also, my coach had a United Tow Brake Controller installed at one time and some of the wiring is still there but it's not wired like the UTB diagram shows, no relay anywhere. But I may revisit the wiring and see if there's something I'm missing.

One final comment and I appreciate Richard chiming in.  You really do need to look at the wiring.  I can’t say, either way, whether Monaco changed the brake signal.  But what I do know, is that later on, when we were working with another member and fixed his cruise control, Monaco had an ECM signal coming out of the ECM. 

That is the one that concerns me now. However, i think that your rig is the same as Richard’s and, no offense nor putting you down, you have not located the proper “ground”.  I’m attaching the print that is almost the “template” for the brake signal going back many years.  Look at it.  Go to the top middle.  There is a yellow section  that is marked “TREADLE VALVE”.  You need to find that on your prints or on your rig.  That is the GROUND that Richard used.  Now, if you trace it, there is, a “brake light” relay…and it sends the positive 12 VDC to the stop lights.  There are two relays.  One works off the ECM.  When you use the Exhaust brake, that relay brings on the third light.  The other relay is actuated from the Treadle valve circuit.

This sounds like beating the dead source.  But, used the UTB instructions.  It needed a positive 12 VDC BRAKE signal. Trace the PO wires…odds are, assuming he had itbworking, that one of the wires in the harness has your Brake Light signal..probably 12 VDC… BUT, think out of the box and pin out the UTB cut off wires for positive as well as ground. All Monaco did when the went to prewired was use an existing signal.  The goofed.  They had the wrong wire….and US GEAR figured it out. Monaco then tapped into the correct output and had, already available, the 12 VDC signal wire…l

BUT, many folks like Richard found the ground switched wire from the Treadle….and then used it to energize the relay coil (T 85 & T86).  Then you run power to T 30 & when the Bosch relay coil is energized, you have the “ignition on” positive signal AKA Brake Light wire on T87.

Thats it…here is a print.  Odds are…you wiring is the same.  

Cruise%20Control%2038071438.dwg 2.pdf

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PXL_20230918_013529610_MP.thumb.jpg.ec76a1e13829be1e5b69a65391987742.jpg

3 hours ago, Tom Cherry said:

One final comment and I appreciate Richard chiming in.  You really do need to look at the wiring.  I can’t say, either way, whether Monaco changed the brake signal.  But what I do know, is that later on, when we were working with another member and fixed his cruise control, Monaco had an ECM signal coming out of the ECM. 

That is the one that concerns me now. However, i think that your rig is the same as Richard’s and, no offense nor putting you down, you have not located the proper “ground”.  I’m attaching the print that is almost the “template” for the brake signal going back many years.  Look at it.  Go to the top middle.  There is a yellow section  that is marked “TREADLE VALVE”.  You need to find that on your prints or on your rig.  That is the GROUND that Richard used.  Now, if you trace it, there is, a “brake light” relay…and it sends the positive 12 VDC to the stop lights.  There are two relays.  One works off the ECM.  When you use the Exhaust brake, that relay brings on the third light.  The other relay is actuated from the Treadle valve circuit.

This sounds like beating the dead source.  But, used the UTB instructions.  It needed a positive 12 VDC BRAKE signal. Trace the PO wires…odds are, assuming he had itbworking, that one of the wires in the harness has your Brake Light signal..probably 12 VDC… BUT, think out of the box and pin out the UTB cut off wires for positive as well as ground. All Monaco did when the went to prewired was use an existing signal.  The goofed.  They had the wrong wire….and US GEAR figured it out. Monaco then tapped into the correct output and had, already available, the 12 VDC signal wire…l

BUT, many folks like Richard found the ground switched wire from the Treadle….and then used it to energize the relay coil (T 85 & T86).  Then you run power to T 30 & when the Bosch relay coil is energized, you have the “ignition on” positive signal AKA Brake Light wire on T87.

Thats it…here is a print.  Odds are…you wiring is the same.  

Cruise%20Control%2038071438.dwg 2.pdf 67.15 kB · 1 download

Thanks again Tom, tomorrow I will have more time and really dig into the wiring and take a good look at the print you have. Today I had a few minutes and poked around with my Fluke tester and discovered something. Whoever installed the UTB system cut in this gizmo into the 'Brake Sig' wire. From what I can tell from a Google search it's a bridge rectifier. But what's crazy is when the constant negative wire is attached to it and brakes are pressed it sends 12v positive to the green wire doubled up in picture. I'm not sure exactly what's going on or how it gets 12v from a negative grounded wire, but this is what UTB was using to get a 12v positive signal for their brake controller. I'll dig into it more tomorrow after reviewing the drawings, but if needed I'll use this rectifier. But I would really like to get rid of anything UTB and have a wiring system I can understand.

Edited by Pudgy Camper
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Is it possible that the wring system UTB used may have messed up what is really supposed to happen with the Brake Signal wire? Meaning that it is a negative wire that is open until you step on the brake pedal.

If that is true, then I would rip out the entire UTB system and start from scratch.

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9 hours ago, Pudgy Camper said:

PXL_20230918_013529610_MP.thumb.jpg.ec76a1e13829be1e5b69a65391987742.jpg

Thanks again Tom, tomorrow I will have more time and really dig into the wiring and take a good look at the print you have. Today I had a few minutes and poked around with my Fluke tester and discovered something. Whoever installed the UTB system cut in this gizmo into the 'Brake Sig' wire. From what I can tell from a Google search it's a bridge rectifier. But what's crazy is when the constant negative wire is attached to it and brakes are pressed it sends 12v positive to the green wire doubled up in picture. I'm not sure exactly what's going on or how it gets 12v from a negative grounded wire, but this is what UTB was using to get a 12v positive signal for their brake controller. I'll dig into it more tomorrow after reviewing the drawings, but if needed I'll use this rectifier. But I would really like to get rid of anything UTB and have a wiring system I can understand.

Still back to basics.  Here is the generic Cruise Control drawing that you need to be using.  OK...OPEN it up.  Go to the Center top.  Look at the TREADLE Valve. There is your diode.  What you have in the picture is a "GEE this might work.." component.  Is it the OEM?  Don't know.  Don't have a picture of the circuit on it.  BUT, it is the diode coming from the Cruise Control Cancel relay.  Yes...your's has 4 terminals.  Monaco did strange things.  Unless you draw a schematic of the Diode and post that, can ONLY guess.  

Now....When you say "Tapped in" that may WELL have been the signal.  This is EXACT same circuit, just drawn a different way from my previous post.  

OK....First....Don't knock finding the signal.  Second, I Think it is supposed to work that way.  SO, my logic.  If you look at the print.  The Diode is what is grounding out the circuit and providing the GROUND that cancels the cruise.  The diode is in there to prevent feedback.  When there is current flowing...the diode allows that current to pass.  SO, when the treadle is pushed, you ground out the coil (Cruise Control Cancel Relay).  Current then flows from terminal 85...through the coil to terminal 86.  Then it goes through the diode and then do the Treadle Valve.  What I THINK is happening is that when you apply the brakes....the treadle valve switch will close.  Then that ground signal actually has "current flowing" through it.  The Diode is acting as a "gateway".  It can sit there all day...but only allows current to flow when you make the signal. Now, on the Anode or the Positive side (green wire), when the Diode allows current to flow, you are getting positive voltage, through the coil of the Cruise Control Relay....at that point, the voltage is still 12 VDC and is going to the ground.  So, that is HOW you are getting POSITIVE 12 VDC, which is what you need. There is actually NOT a circuit across the coil of the relay....until the diode "senses" current.  Once it says...HEY...I feel a tingle...as in the brake pedal is attached, it allows the Positive from the Ignition Switch to flow through the Coil of the Cruise Cancel relay....and when you measure it, on the Anode (green) side of the diode...it is 12 VDC Positive.  

YES, it is a bit confusing...and if we had NOT had this problem of a bad diode causing the brakes NOT to cancel the cruise last week, I would NOT have been able to even attempt at explaining it.

What I would say....  LEAVE IT ALONE.  Use your UTB tap and now you do NOT have to go through a relay.  Richard picked his up from the Treadle....I suspect on the over side or on a switched GROUND somewhere else.  

This is, I think, the way it will work.  SO....here is your test...

First...  Start the engine.  Now, put your VOM on the green wire.  Press the brake.  Do you get a signal (measured to ground) or 12 VDC when you press the brakes?  OK.  NOW, turn ON the cruise.  Push the resume button.  That will take you to HIGH idle.  You should NOT have a signal (12 VDC).  Tap or push the brakes.  Then you should get the 12 VDC signal.  If all that works....  DRIVE ON.

This is one MORE CRAZY but Unique way of getting the signal. I'm going out on a limb here.  Either the PO was really sharp at measuring and trouble shooting and knew how to do a "Cause and Effect" testing...  OR...  US Gear told him exactly WHERE to get the signal, the easiest...and he wired it that way.

CHUCKLE...  I admit that my "Don't tear out what you don't know advice" was generic.  BUT, if I am right...and this is working...and it sort of "makes sense to me", then when we, the "Moderating Staff" tell folks to trouble shoot and make sure that they know what they are doing....as they decide or feel the need to rewire something...especially when it is "WORKING" but they want it OEM, then sometimes they forget the "If it AIN'T BROKE....Don't FIX IT" common sense rule.

I WILL verify my logic with my chief Electronic's Mentor....and let you know.

For the INTERIM...  I would proceed with all the "Grunt Work" and get your new wiring back to the rear of the MH. NOW.. I HAVE NO IDEA about the wiring size of the infamous BLUE wire that you will be running to your 7 pin adapter.  You said the UTB wiring had several wires in it.  Have you determined where they are terminated at the rear? Have you deterermined if they are terminated at the front. If any of them are #12...then I would inspect and possibly use them.  NOW...  There is an old "TRICK" that might be used.  When a home audio installer does work, sometimes it is not possible to get enough "gain" or current to a speaker.  The British use a term called "Bi-Wiring".  In stereo installations, having two pairs or wire on each speaker terminal reduces the resistance...  Here is an explanation about circuits....

Pair 2 wires of any size will not double the amp capacity but at best increase 50 percent or one size stronger like 4 to 3 or 10 to 8. Example: 8 awg and bigger is high a rating and cannot Double to use for 6 awg. Normally 14 or 12 is the limit.

OK....in your case.  Say there are TWO wires going back in the bundle.  If they are #14, then by pairing them and using them as a parallel run, you could bump the current from 15 A on the #14 to 20 A on the pair.  NOW, this, of course, depends on having GOOD connections...

SO, just an idea....as to how you might save yourself a bunch of work.  BUT...that is your call....just options.

2004 Generic Cruise Control - ALL DIESEL.pdf

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1 hour ago, Tom Cherry said:

Still back to basics.  Here is the generic Cruise Control drawing that you need to be using.  OK...OPEN it up.  Go to the Center top.  Look at the TREADLE Valve. There is your diode.  What you have in the picture is a "GEE this might work.." component.  Is it the OEM?  Don't know.  Don't have a picture of the circuit on it.  BUT, it is the diode coming from the Cruise Control Cancel relay.  Yes...your's has 4 terminals.  Monaco did strange things.  Unless you draw a schematic of the Diode and post that, can ONLY guess.  

Now....When you say "Tapped in" that may WELL have been the signal.  This is EXACT same circuit, just drawn a different way from my previous post.  

OK....First....Don't knock finding the signal.  Second, I Think it is supposed to work that way.  SO, my logic.  If you look at the print.  The Diode is what is grounding out the circuit and providing the GROUND that cancels the cruise.  The diode is in there to prevent feedback.  When there is current flowing...the diode allows that current to pass.  SO, when the treadle is pushed, you ground out the coil (Cruise Control Cancel Relay).  Current then flows from terminal 85...through the coil to terminal 86.  Then it goes through the diode and then do the Treadle Valve.  What I THINK is happening is that when you apply the brakes....the treadle valve switch will close.  Then that ground signal actually has "current flowing" through it.  The Diode is acting as a "gateway".  It can sit there all day...but only allows current to flow when you make the signal. Now, on the Anode or the Positive side (green wire), when the Diode allows current to flow, you are getting positive voltage, through the coil of the Cruise Control Relay....at that point, the voltage is still 12 VDC and is going to the ground.  So, that is HOW you are getting POSITIVE 12 VDC, which is what you need. There is actually NOT a circuit across the coil of the relay....until the diode "senses" current.  Once it says...HEY...I feel a tingle...as in the brake pedal is attached, it allows the Positive from the Ignition Switch to flow through the Coil of the Cruise Cancel relay....and when you measure it, on the Anode (green) side of the diode...it is 12 VDC Positive.  

YES, it is a bit confusing...and if we had NOT had this problem of a bad diode causing the brakes NOT to cancel the cruise last week, I would NOT have been able to even attempt at explaining it.

What I would say....  LEAVE IT ALONE.  Use your UTB tap and now you do NOT have to go through a relay.  Richard picked his up from the Treadle....I suspect on the over side or on a switched GROUND somewhere else.  

This is, I think, the way it will work.  SO....here is your test...

First...  Start the engine.  Now, put your VOM on the green wire.  Press the brake.  Do you get a signal (measured to ground) or 12 VDC when you press the brakes?  OK.  NOW, turn ON the cruise.  Push the resume button.  That will take you to HIGH idle.  You should NOT have a signal (12 VDC).  Tap or push the brakes.  Then you should get the 12 VDC signal.  If all that works....  DRIVE ON.

This is one MORE CRAZY but Unique way of getting the signal. I'm going out on a limb here.  Either the PO was really sharp at measuring and trouble shooting and knew how to do a "Cause and Effect" testing...  OR...  US Gear told him exactly WHERE to get the signal, the easiest...and he wired it that way.

CHUCKLE...  I admit that my "Don't tear out what you don't know advice" was generic.  BUT, if I am right...and this is working...and it sort of "makes sense to me", then when we, the "Moderating Staff" tell folks to trouble shoot and make sure that they know what they are doing....as they decide or feel the need to rewire something...especially when it is "WORKING" but they want it OEM, then sometimes they forget the "If it AIN'T BROKE....Don't FIX IT" common sense rule.

I WILL verify my logic with my chief Electronic's Mentor....and let you know.

For the INTERIM...  I would proceed with all the "Grunt Work" and get your new wiring back to the rear of the MH. NOW.. I HAVE NO IDEA about the wiring size of the infamous BLUE wire that you will be running to your 7 pin adapter.  You said the UTB wiring had several wires in it.  Have you determined where they are terminated at the rear? Have you deterermined if they are terminated at the front. If any of them are #12...then I would inspect and possibly use them.  NOW...  There is an old "TRICK" that might be used.  When a home audio installer does work, sometimes it is not possible to get enough "gain" or current to a speaker.  The British use a term called "Bi-Wiring".  In stereo installations, having two pairs or wire on each speaker terminal reduces the resistance...  Here is an explanation about circuits....

Pair 2 wires of any size will not double the amp capacity but at best increase 50 percent or one size stronger like 4 to 3 or 10 to 8. Example: 8 awg and bigger is high a rating and cannot Double to use for 6 awg. Normally 14 or 12 is the limit.

OK....in your case.  Say there are TWO wires going back in the bundle.  If they are #14, then by pairing them and using them as a parallel run, you could bump the current from 15 A on the #14 to 20 A on the pair.  NOW, this, of course, depends on having GOOD connections...

SO, just an idea....as to how you might save yourself a bunch of work.  BUT...that is your call....just options.

2004 Generic Cruise Control - ALL DIESEL.pdf 266.3 kB · 1 download

Hi Tom, here is a hand drawn wire schematic of what I'm dealing with. The rectifier/diode in my picture and on my sketch is definitely not OEM and I believe it's part of the UTB system that was unprofessionally installed at some point. This aligns with a long list of shoddy work the previous owner did that I've been correcting the last 4 months. The splice points on my sketch (labeled 1,2,3) where done with cheap crimp butt splices, (yellow in fact, the wrong size) and tells me this was certainly something the previous owner did or had done. This is why I want to remove all the UTB stuff and start from scratch with my own wiring.

This afternoon I plan to look and test everything again with the rig running and the wife pressing the brake pedal. PXL_20230919_150657348.thumb.jpg.2c7de76147dfb60b6358c282cb98800a.jpg

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17 minutes ago, Pudgy Camper said:

Hi Tom, here is a hand drawn wire schematic of what I'm dealing with. The rectifier/diode in my picture and on my sketch is definitely not OEM and I believe it's part of the UTB system that was unprofessionally installed at some point. This aligns with a long list of shoddy work the previous owner did that I've been correcting the last 4 months. The splice points on my sketch (labeled 1,2,3) where done with cheap crimp butt splices, (yellow in fact, the wrong size) and tells me this was certainly something the previous owner did or had done. This is why I want to remove all the UTB stuff and start from scratch with my own wiring.

This afternoon I plan to look and test everything again with the rig running and the wife pressing the brake pedal. PXL_20230919_150657348.thumb.jpg.2c7de76147dfb60b6358c282cb98800a.jpg

OK....This is getting confusing....and I talked to my mentor.  What you have is just a "single diode"  When you said DIODE, I thought you mean the Monaco Diode in the Cruise Control relay.  NOW, it gets a little murky...so one question at a time.

Is the "UTB" Controller STILL in the cabin or has it been pulled and all you have is the 4 pin end?  HOPEFULLY that is all you have.  IF all you have is the 4 Pin connector and NOT the "controller"....then it works.  BUT, it is gonna take a while to noodle that out....

Next up.  When you labeled Relay 2 or Monaco #2, JUST to verify....you labeled the wire as Brake Signal.  It, from the drawing, should be pin 85 on that Relay 2 which is also tied or connected to pin 85 on Relay 3.  EXACTLY, looking at the relay and the relay socket....which PIN NUMBER is the the brake signal?

NEXT..  GOD ONLY KNOWS WHY the 4 pin bridge was used.  LOOK AT IT.

 https://electronics.stackexchange.com/questions/609201/what-happens-if-you-feed-dc-into-a-bridge-rectifier

It LOOKS like the Negative is just a SINGLE pin going to a Positive.  For the LIFE of me, I can't quite noodle out how it turns POSITIVE with voltage.  The Diode is there to prevent a feedback....BUT WHY.  We can't explain it until we see the terminal numbers....so here's the deal..

FIRST....assumption is you have NO CONTROLLER still mounted.....otherwise it confuses me.  SO, if the 4 pin is just hanging there....then that is fine.....

NEXT....IF IT WORKS....then don't mess with it.....  BUT, I do understand your concerns.  You can get the specs on the DIODE by googling or see what is printed on it.  From the looks of the picture....then the 4 diode bridge just has ONE diode in use.  Again... WHY....GOD only knows

Once you get the answers about whether or NOT the old UTB Controller is hooked up and then maybe we can figure it out.  If you get the diode specs, then if the bridge ever fails, you just buy ONE of the diodes and follow the polarity and put in a new one.  

That's it for now.  I'm willing to make good odds that US Gear came up with this circuit....as they KNEW more about Monaco's crazy braking system than maybe even Monaco...

The REST is still valid.  IF you have 2 #14 going to the back....then use them.  If you have a #12...I would fix the connections that concerns you and use that.  BUT, it is your rig and your "want it this way"...

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10 minutes ago, Tom Cherry said:

OK....This is getting confusing....and I talked to my mentor.  What you have is just a "single diode"  When you said DIODE, I thought you mean the Monaco Diode in the Cruise Control relay.  NOW, it gets a little murky...so one question at a time.

Is the "UTB" Controller STILL in the cabin or has it been pulled and all you have is the 4 pin end?  HOPEFULLY that is all you have.  IF all you have is the 4 Pin connector and NOT the "controller"....then it works.  BUT, it is gonna take a while to noodle that out....

Next up.  When you labeled Relay 2 or Monaco #2, JUST to verify....you labeled the wire as Brake Signal.  It, from the drawing, should be pin 85 on that Relay 2 which is also tied or connected to pin 85 on Relay 3.  EXACTLY, looking at the relay and the relay socket....which PIN NUMBER is the the brake signal?

NEXT..  GOD ONLY KNOWS WHY the 4 pin bridge was used.  LOOK AT IT.

 https://electronics.stackexchange.com/questions/609201/what-happens-if-you-feed-dc-into-a-bridge-rectifier

It LOOKS like the Negative is just a SINGLE pin going to a Positive.  For the LIFE of me, I can't quite noodle out how it turns POSITIVE with voltage.  The Diode is there to prevent a feedback....BUT WHY.  We can't explain it until we see the terminal numbers....so here's the deal..

FIRST....assumption is you have NO CONTROLLER still mounted.....otherwise it confuses me.  SO, if the 4 pin is just hanging there....then that is fine.....

NEXT....IF IT WORKS....then don't mess with it.....  BUT, I do understand your concerns.  You can get the specs on the DIODE by googling or see what is printed on it.  From the looks of the picture....then the 4 diode bridge just has ONE diode in use.  Again... WHY....GOD only knows

Once you get the answers about whether or NOT the old UTB Controller is hooked up and then maybe we can figure it out.  If you get the diode specs, then if the bridge ever fails, you just buy ONE of the diodes and follow the polarity and put in a new one.  

That's it for now.  I'm willing to make good odds that US Gear came up with this circuit....as they KNEW more about Monaco's crazy braking system than maybe even Monaco...

The REST is still valid.  IF you have 2 #14 going to the back....then use them.  If you have a #12...I would fix the connections that concerns you and use that.  BUT, it is your rig and your "want it this way"...

Hi Tom, thanks for all your help, really appreciate it! I agree, it's super confusing. I have an electrical background and have 30+ years under my belt as a Journeyman Electrician but still get confused by 12vdc circuits and automobile electrical systems. That is why I was so confused when I started peeling back the layers of the onion in my rigs brake signal system. The UTB controller is still mounted in the rig, but I disconnected it when I started my investigating. I started with the UTB controller 4 wire connector and started tracing it backward towards the FRB, that's how I confirmed the rectifier/diode gizmo was part of the UTB system. Then discovered the shoddy 2-#14s running under the belly of the coach to the rear UTB receptacle. I really hoped I would find the negative brake signal trigger that others have used and it would have been a piece of cake from there. I'll keep at it and will report back what I come up with after more testing and investigating. I'll take a close look at the Monaco #2 brake relay pin connections like you suggested. 

As for the 'Blue' trailer brake controller signal wire, I found a bundle of 3-#12 wires (red, white and blue) coiled up near my fuel filters in the engine bay. I put a circuit tracer on one of them and found them up front in the drivers side console area! So I'm good there, I'll use the Blue #12 from my controller to the 7 pin plug on the receiver. I've already tested my 7 pin plug at the receiver hitch and everything works as it should there, just need to hook up that #12 blue signal wire.

Again thanks for your help, I feel I'm making progress and getting closer to getting this coach squared away.

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1 hour ago, Pudgy Camper said:

Hi Tom, thanks for all your help, really appreciate it! I agree, it's super confusing. I have an electrical background and have 30+ years under my belt as a Journeyman Electrician but still get confused by 12vdc circuits and automobile electrical systems. That is why I was so confused when I started peeling back the layers of the onion in my rigs brake signal system. The UTB controller is still mounted in the rig, but I disconnected it when I started my investigating. I started with the UTB controller 4 wire connector and started tracing it backward towards the FRB, that's how I confirmed the rectifier/diode gizmo was part of the UTB system. Then discovered the shoddy 2-#14s running under the belly of the coach to the rear UTB receptacle. I really hoped I would find the negative brake signal trigger that others have used and it would have been a piece of cake from there. I'll keep at it and will report back what I come up with after more testing and investigating. I'll take a close look at the Monaco #2 brake relay pin connections like you suggested. 

As for the 'Blue' trailer brake controller signal wire, I found a bundle of 3-#12 wires (red, white and blue) coiled up near my fuel filters in the engine bay. I put a circuit tracer on one of them and found them up front in the drivers side console area! So I'm good there, I'll use the Blue #12 from my controller to the 7 pin plug on the receiver. I've already tested my 7 pin plug at the receiver hitch and everything works as it should there, just need to hook up that #12 blue signal wire.

Again thanks for your help, I feel I'm making progress and getting closer to getting this coach squared away.

To close this out....HOPEFULLY...

You are GOOD to GO.  Don't understand the blasted negative ground switching and such.  Also, don't understand why Constant Ground goes 12 VDC.  There ain't any hamsters inside that Diode Bridge.  BUT, it works....and you also found your hidden magic (Christmas present) BLUE wires.  THAT is great.

Advice.  Unless you think there are major issues with the PO's circuit wiring...I would tape over the 4 pin harness and let things be.  BUT, the UTB is a popular item.  Might be that you can pull out the controller and the connector....and even, as a bonus, ship off the 4 wire connector (which you don't need) and peddle that on Ebay.  YOU NEVER KNOW.

Next, get the specs off the Bridge and order a diode online.  Have it as a spare.  You MIGHT also look at the circuit and find the INFAMOUS Monaco one.  Probably a stock item and polarized and click in like a fuse.  Get one of them.  BOTH are critical to your braking.  The Monaco one controls the Brake Cancels Cruise relay.  Something you really want to work.

If my mentor can explain and I can translate into English, I'll get back to you

BUT, as you button it up, the Pin or Terminal number (from the Relay for the CUT and Insert a Diode line would be helpful.

That's it..  Good Luck...

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On 9/19/2023 at 11:21 AM, Tom Cherry said:

To close this out....HOPEFULLY...

You are GOOD to GO.  Don't understand the blasted negative ground switching and such.  Also, don't understand why Constant Ground goes 12 VDC.  There ain't any hamsters inside that Diode Bridge.  BUT, it works....and you also found your hidden magic (Christmas present) BLUE wires.  THAT is great.

Advice.  Unless you think there are major issues with the PO's circuit wiring...I would tape over the 4 pin harness and let things be.  BUT, the UTB is a popular item.  Might be that you can pull out the controller and the connector....and even, as a bonus, ship off the 4 wire connector (which you don't need) and peddle that on Ebay.  YOU NEVER KNOW.

Next, get the specs off the Bridge and order a diode online.  Have it as a spare.  You MIGHT also look at the circuit and find the INFAMOUS Monaco one.  Probably a stock item and polarized and click in like a fuse.  Get one of them.  BOTH are critical to your braking.  The Monaco one controls the Brake Cancels Cruise relay.  Something you really want to work.

If my mentor can explain and I can translate into English, I'll get back to you

BUT, as you button it up, the Pin or Terminal number (from the Relay for the CUT and Insert a Diode line would be helpful.

That's it..  Good Luck...

Well I finally got it figured out. I should have used my Power Probe from the start and it might have saved me some frustration. When hooked up it shows if a wire is either positive or negative automatically without changing settings or dials. At first I was using my Fluke meter and I wasn't very thorough in my investigation. 

However, I finally found a good brake signal but it's different from what others have discovered. I found that the #155b wire coming out of the Monaco #2 box, labeled 'brake lamp' is normally grounded but when the brake pedal is pressed (with engine running), it becomes a 14v positive brake signal. So I didn't need to add a relay. I also discovered that this #155b wire is coming off of the #30 terminal of the brake relay. I ended up keeping the UTB diode gizmo that I showed previously and kept it hooked up just as UTB did, as it didn't seem to make any difference with or without it, but I decided to keep it for now. I removed every other piece of the UTB system.

I'm guessing that Monaco changed something in 2004 or someone changed some wiring somewhere on the coach that actually makes this a very simple process if you know what wire to look for. I wanted to share my findings and post a few pictures that show exactly what I ended up with. Thanks to everyone for your help, especially you Tom, for helping me out on this one!

 

PXL_20230922_0134211032.thumb.jpg.5ea2c36cb8321b3fd07f1a2b1cff1da4.jpgPXL_20230922_0140007562.thumb.jpg.6b78e236e61965252f18db0b69ab6152.jpgPXL_20230922_0138081082.thumb.jpg.90c85cfea0eeadfad0ac8505eef3012b.jpg

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2 hours ago, Ivan K said:

I suppose you verified that the power doesn't come on with engine or jake brake, right?

I haven't yet, I will verify with a test drive this weekend that everything is working the way it should. From what I know, my brake lights don't come on with my engine brake. This wire activates the brake lamps, but keeping my fingers crossed its NOT tied into the engine brake!

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3 hours ago, Pudgy Camper said:

I haven't yet, I will verify with a test drive this weekend that everything is working the way it should. From what I know, my brake lights don't come on with my engine brake. This wire activates the brake lamps, but keeping my fingers crossed its NOT tied into the engine brake!

You're WELCOME.  I was gonna suggest that you tap into RELAY 3 and use the Brake Light Signal that goes to the Lamp relay.  BUT, I didn't want to confuse you.  I personally would remove the DIODE....BUT, if it works....then FINE. I still suspect that the PO was being guided by US Gear as they fully understood the circuit.

Good Luck and let us know.

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