ziaptrn Posted May 18 Share Posted May 18 (edited) Hello all. I'm at a rally and helping a friend who owns a 2005 Dynasty 42' with tag axle and no Multiplex system. They have experienced a sudden loss of brake lights for the rig and tow car both. There is no trailer brake controller installed. The parking lights and turn signals all work properly. I have reviewed every post here on Monacoers that I can find concerning "no brake lights" and am asking the hive mind (!) for assistance. 1. The 15 amp fuses are intact, tested, and replaced with new fuses for front run bay and rear run bay next to the relays for the brake lights and the engine brake. If there is another fuse I'm missing, I can't find it and I have checked with the 05 Schematics posted here on Monacoers. 2. The rear relay has been replaced with a new one, and also swapped with the front relay, then swapped those around with no change in function. Both front and rear bays show the red light on the PCB illuminated, so I am assuming that power is present in both locations. the green and yellow lights do not illuminate at all when running and brake pedal depressed. 3. The pressure switches are in the front in the generator compartment, and I am attaching a photo. There are 2 switches with what appears to be two sensors (?) below. I tested the round black switches on the top for continuity using a multitester, and the left switch reads *nothing* (blank screen - not even '1' - for infinite) when tested for continuity at rest, and the right switch shows continuity of 80/800ohms (not sure of units/decimal) at rest. Both switches click and show zero resistance with key on and brake pedal depressed. So it seems that they are working? The initial resistance reading on the left is the only deviation that I can identify; I've never seen something show "nothing/blank" and then go to zero resistance - and this behavior is different than the switch on the right which reads some continuity with resistance at rest, then goes to zero with key on and brake applied. 4. The two lower switches/sensors show zero continuity (1) at rest, and zero resistance with key on and brake pedal depressed. So they seem to be working? 5. I have cleaned and re-tightened all of the connections to the pressure switches and the sensors, as well checking all of the related plugs that run to/from the PCBs. All are snug. 6. The main connector that goes to the rear lights (both sides) was pulled apart, cleaned with WD40, and re-connected. This is the connection on the roadside that Mr. Hutto mentions in his posting. 7. We have tested all of the above with the engine brake on and off, and it doesn't make any difference as far as the brake lights not working. 8. The owner has reported some erratic gauge operation from time to time (rare) which has always resolved after a few minutes or bumps in the road. I attribute this to the Monaco daisy-chaining of grounds under the dash, but mention it just because...well, there is so much that I do NOT know..... All of this and still no joy. What am I missing or what should I check next? John Edited May 18 by ziaptrn clarification Link to comment Share on other sites More sharing options...
jacwjames Posted May 18 Share Posted May 18 On my 2002 Windsor there is a wiring harness connector that ties the wiring for the lights and harness for the trailer connector. On mine it was buried in the wiring at the back. I only found it when I was trouble shooting the trailer plug in. I never unplugged it so don't know what would happen if it became unplugged. Link to comment Share on other sites More sharing options...
ziaptrn Posted May 18 Author Share Posted May 18 I forgot to mention that I have also looked at the 7-pin connector for the trailer and it seems fine. No obvious corrosion, etc. but I haven't dis-assembled it. the wires are sealed in the back of the plug and are intact until they disappear in a morass of wires underneath. Thanks, Jim...I'll look there next and see if I can find the connector that you mention. John Link to comment Share on other sites More sharing options...
waterskier_1 Posted May 18 Share Posted May 18 Just a reminder, you have to have air pressure for the brake lights to work. - Rick N 1 Link to comment Share on other sites More sharing options...
ziaptrn Posted May 19 Author Share Posted May 19 Hey Rick & Jim J - 1. yes, checking with air in system. 2. I found the tow plug connector underneath the rig. I pulled and cleaned the tow plug connector and re-attached. Still no joy. After re- re- reading the posts, I'm catching on, I think. There are 4 pressure switches; Two on the Primary Circuit, and Two on the Secondary. The upper switches (in the photo that I provided) are for cruise control (I think), and the lower switches are for the brake lights. Since they are wired in parallel, should both fail, the brake lights won't work. If only one fails, the lights will work until the 2nd one fails. If I jumper the brake light switches and the brake lights come on, then we know that the switches are bad. Correct? John Link to comment Share on other sites More sharing options...
ziaptrn Posted May 19 Author Share Posted May 19 Following up: Jumping the harness at the pressure switches for the brake lights did not change anything. I verified that the 7pin plug at the rear does have power with left and right turn signals, but not for brakes. Awaiting enlightenment. I will continue to review the schematics to find what I am missing. John Link to comment Share on other sites More sharing options...
pwhittle Posted May 19 Share Posted May 19 The top round ones are for the brake lights, the lower ones are for cruise cancel. Paul Link to comment Share on other sites More sharing options...
ziaptrn Posted May 19 Author Share Posted May 19 Thank you for the assist. So now I know to focus on the two upper switches. That is a great help. Thanks, Paul! John Link to comment Share on other sites More sharing options...
ktloah Posted May 19 Share Posted May 19 I lost my brake lights on our way to FL. Tested as you did and decided to replace both brake light switches being they were 20 yrs old. Bought them thru Amazon, had them delivered to CG. Fixed my problem...good luck Link to comment Share on other sites More sharing options...
MyronTruex Posted May 19 Share Posted May 19 https://www.youtube.com/watch?v=usiP4myzxxU At the 7 minute mark is a picture of a bad dash ground. ------------------------------------------------------------------- --------------------------------------------------------------------------- The following attachment file is a word document provided as a response to the OP's first comments. After messing up a long post the other day I am erroring on the side of caution posting it this way. ------------------------------------------------------------------------------------------------------------------------------------------ 1. The 15 amp fuses are intact, tested, and replaced with new fuses for front run bay and rear run bay next to the relays for the brake lights and the engine brake. If there is another fuse I'm missing, I can't find it and I have checked with the 05 Schematics posted here on Monacoers. Use a voltmeter to verify there is voltage on each end of the fuses. ----------------------------------------------------------------------------------------------- 2. The rear relay has been replaced with a new one, and also swapped with the front relay, then swapped those around with no change in function. Both front and rear bays show the red light on the PCB illuminated, so I am assuming that power is present in both locations. the green and yellow lights do not illuminate at all when running and brake pedal depressed. Take voltage measurements of all of the pins socket with the relay removed. Do this with the brake pedal pushed and also NOT pushed. Post a picture of the relay and part number if possible. Doing this should help determine if the signal is getting this far. And with some analysis, a substitute voltage via a fused lead can help “half split” the problem. 2. The pressure switches are in the front in the generator compartment, and I am attaching a photo. There are 2 switches with what appears to be two sensors (?) below. I tested the round black switches on the top for continuity using a multimeter, and the left switch reads *nothing* (blank screen - not even '1' - for infinite) when tested for continuity at rest, and the right switch shows continuity of 80/800ohms (not sure of units/decimal) at rest. Both switches click and show zero resistance with key on and brake pedal depressed. So it seems that they are working? The initial resistance reading on the left is the only deviation that I can identify; I've never seen something show "nothing/blank" and then go to zero resistance - and this behavior is different than the switch on the right which reads some continuity with resistance at rest, then goes to zero with key on and brake applied. Use a voltmeter instead of an ohmmeter. Take the readings again and post. An ohmmeter can really fool you. Your fingertips alone will cause a reading if touching the probes. The devices may appear to open and close via an ohmmeter, but bad contacts will not carry a load. 8. The owner has reported some erratic gauge operation from time to time (rare) which has always resolved after a few minutes or bumps in the road. I attribute this to the Monaco daisy-chaining of grounds under the dash, but mention it just because...well, there is so much that I do NOT know..... Glad you are mentioning this. Often, I have to ask forty questions to elicit what may seem trivial, but is in fact critical. With such poor documentation on this, as I spent an hour looking over schematics of various year units, it may be prudent to “fix the obvious” Obvious, meaning you have a clue/problem that is known. Perhaps it has reared its ugly head in a new way. Maybe it has just gotten a tiny bit worse and now that precious/critical ground is just not enough to make some relay function. If things have not been sorted soon, I would go to one of the gauges that is effected when the ground is acting up. Find the ground side of the gauge and run a new ground to it. This may be a waste of time but at least the gauges should work properly after that. With a known good ground for your meter, measure the voltage on one of the gauges, both sides. That is, power and ground. IF you find any voltage at all on the cold/ground side, you have a bad ground. In a recent video I made, my buddy’s intermittent crazy gauges problem was found to be a bad pin connection on a molex plug under the dash. The connector wire was simply bypassed and the problem was gone for good. Finding a good ground for a meter is a serious problem in an RV. Plug in a short extension cord and then secure your negative probe into the ground hole of the extension cord. Jam a golf tee that has been whittled down or a small Phillips screwdriver. Make sure you have a good connection. Brake lights inop.docx Link to comment Share on other sites More sharing options...
Yoaks5 Posted May 19 Share Posted May 19 When my brake lights were not working it was burnt wire pins in the J connectors. Those are the big round connectors in your front run bay that the wires exit the bay threw. The po had water getting in the bay and it burnt up a few of these connectors. Link to comment Share on other sites More sharing options...
MyronTruex Posted May 19 Share Posted May 19 I saw Cannon/Barrel type connectors on a schematic or two but was not able to discern their location well enough to suggest what Youaks5 mentions. That is a great idea and place to look for sure. Some pictures of that aree would really help as well. Link to comment Share on other sites More sharing options...
ziaptrn Posted May 19 Author Share Posted May 19 Update - and thanks So much for the feedback, guys. Not my rig, but I'm trying to help a fellow traveler! 1. I checked every fuse in the front and rear run bays All good except one for DGN Power. It was a 1 amp fuse. Replaced it, no change. 2. I checked voltage at the brake pressure switches, and get full power at both of them. I then jumped the pressure switches directly with a known good jumper, and no joy. I jumped them individually and cleaned all contacts and re-tightened. No change. The pressure switches do conduct full power across when the pedal is pressed; engine running and aired up. I would think that this rules out the pressure switches as the culprit, as bypassing them completely did not affect anything. 3. I will check the relay pins for voltage on front and rear next. 4. I'm searching for the grounding buss bar in the front but not having luck in locating. I found the huge generator bolt ground to the chassis frame, and I have confirmed good ground with multimeter and yes it can be a problem. I've also used a 12v test light that also illuminates properly so I know the power and ground are there. 4. I'm not sure what the symptoms would be if a bad relay. Any assist in this would be helpful. I understand what relays do in theory, but am not exactly sure what symptoms would be if they were defective other than not relaying current. RRB Brake Light Relay photo is attached. FRB Engine Brake Relay is Bosch 12033862 12v 20/30A The owner is going to remove a pressure switch and try to source some locally today, and also get another relay. Naturally this is Sunday, so tomorrow may be next available time for parts. Thanks again to all who have responded. If nothing else, we are learning tons 🙂 Link to comment Share on other sites More sharing options...
jacwjames Posted May 19 Share Posted May 19 There is a set of wiring diagrams for a 2005 Dynasty in the downloads section. I quickly scrolled through it, I did not find anything specific to the brake or turn signal light for dash wiring but I did find the trailer brake control diagram on page 205 and on the rear tow harness wiring on page 208, which does include turn signals for steering column. If you do have a connector that would disable the tow plug you might try disconnecting and see if that has any impact to chassis turn & brake lights. Link to comment Share on other sites More sharing options...
Tom Cherry Posted May 19 Share Posted May 19 Many good comments and informative. My $00.02…relays are notorious offenders. The 5 pin Bosch can we swapped with one from the house or the chassis. Never depend on a DVOM. Yes….coil resistance can be checked. Yes, contracts. I’d swap or find the spare 5 pin. The 4 pin….?? Don’t have one….focus on it. Look at the print. Is the coil getting voltage? GOOD. NOW, pull the two contact wires off..push on brake. Jumper the (30 & 87???) wires. Works? Bad relay. no joy….i’d start with the fuse and work my way through. When you press the brake, you need to follow the prints. Remember, Monaco LOVED NEGATIVE SWITCHING on the brake circuit. See which ones are open. Then jumper close. right now it is a crap shoot to start throwing parts at it. Test, troubleshoot and verify… Link to comment Share on other sites More sharing options...
Steve P Posted May 19 Share Posted May 19 John - you are a good friend, and an extremely persistent troubleshooter. I have a similar intermittent problem, and I hope to learn from this post how to resolve mine (which seems to come and go with the toad connected). Please continue to post your very methodical findings. There are numerous YouTube videos on testing relays. Be sure not to apply 12V to a 5V relay if you find one. The pins on your relay should be numbered to correspond to the diagram. If you apply 12V across 85 & 86, you should hear the relay click, and be able to confirm with an ohmmeter or continuity checker that the relay is toggling between 87 and 87a (my uninformed assumption would be that braking would apply voltage to 85/86, but it may remove it instead. Let's get a more detailed explanation from @Tom Cherry for what he means by " Monaco LOVED NEGATIVE SWITCHING on the brake circuit. See which ones are open. Then jumper close." Maybe it's like what I describe as removing the voltage? Or maybe grounding a pin? The wiring diagram "should" reveal the use of the relay, but one would need to be adept at reading the diagrams. I've printed mine out in color and it's still a mind-boggling rats nest. I would love to have a 2 hour side by side tutorial with someone who did this for a living just to up my game. I share your appreciation for learning! Link to comment Share on other sites More sharing options...
Tom Cherry Posted May 19 Share Posted May 19 OK….OMG…a Detailed EXPLANATION of Monaco’s fetish for Ground or Negative switching. @Frank McElroy would be the one to teach such a seminar. SERIOUSLY. I have tried to help folks over the years diagnose and trouble shoot the Missing Brake Lights. It varies from Rig to RIG and also from “wiring diagram style”… CLEAR? I don’t do well on the Dynasty “Pin and Harness” system. BUT even on the mid to late lower ends….with a more typical line and connection format….these BRAKES are tough. I will also say the MONACO FAILED….when they developed the “Trailer” brake harness…..that Simple 5 wire bundle…they did NOT EVEN get it right. US Gear (Tow Brake) had to sit down with them and explain why they picked the WRONG contacts and botched it. US Gear published the correct circuit…because now they actually could follow the wires…and understood how Negative switching worke. BOTTOM LINE. You can NEVER assume that a relay coil is always POSITIVE switched. Personnally, and I have spent DAYS (Weeks?) printing and marking and trading the path…as well as the Polarity of coil wires. IF Monaco had a “overlay” or a symbol that said…”This is a Ground Switched Relay….” But, I also recall, that they even topped themselves….had a relay that had to have TWO conditions. The ground could be SWITCHED…and thr POSITIVE could be SWITCHED…so you have to follow the circuit on BOTH sides of the coil. Not quite Spock Three Dimensional chess…but getting close…of course a 1040 form comes to mind. Myron has great insight. You work which side (front to back) or (back to front) that makes the most sense to you. Always LOOK…does the Negative (usually pin86) go to a common point or have the GROUND symbol… THEN, on some circuits…there is a FEEDBACK from the ECM. I wish I had a clearcut outline and could pass it on,,, Link to comment Share on other sites More sharing options...
MyronTruex Posted May 19 Share Posted May 19 Just a quick thought while gathering information. Do the lights flash if you turn the emergency flasher button on? This will not likely give me more clues, perhaps even more questions. I looked at the schematic and unfortunately, it stops at the turn signal switch. So my opinion is that everything from the dash back is ok. That is, no issues with relays etc in the rear. Jumping the pressure switches and taking voltage measurements while doing so will prove they are working under load. Your issue appears to be between the pressure switches and the turn signal path. Link to comment Share on other sites More sharing options...
ziaptrn Posted May 20 Author Share Posted May 20 Latest update/summary: 1. Took all of the individual light bulbs out of their sockets, tested and viewed for filament integrity, cleaned and replaced. Just in case it was a burned out bulb? No change. 2. Replaced both Rear Brake relay in RRB and Engine Brake Relay in FRB with known-good relays from my rig (2008 Dynasty). Relays were same as those removed from the 2005. No change with two known-good relays in place. 3. Found a burned wire in a molex connector in the FRB that has resulted in inop docking lights but is unrelated to the current problem. The owner was aware of the inop docking lights, but now knows what to repair so that they can work again. 4. The emergency flashers work correctly. 5. The turn signals work correctly. 6. There is power to the 7-blade trailer plug and the toad turn signals work properly as far as energizing the proper blades on the connector. 7. I see where the grounding wires are secured on individual things that look like bolts in both FRB and RRB. So I'm not looking for the type of buss bar that I thought. Anyways - all of the nuts securing all of the wires to the grounds are tight and I get no resistance between these and other points on the frame. I think this means that the grounds are not the issue - at least not at the FRB and RRB as they relate to the relays and pressure switch functions. For Mr. Tom - the white wires from the harness to the round pressure switches are live with 12V all the time. Key off, ignition off, etc. Not sure if this is meaningful other than it makes sense that the switches are normally open; when air is applied via the treadle valve, the switches both click loudly, close, and continuity is good (0 resistance). I understand that it is possible that they show no resistance yet still won't work because they can't carry an adequate electrical load, but when I bypass the switches altogether with copper wire, the brake lights still don't work. I would think that the brake lights would come on as soon as powered up with key on if jumpered, but this does not happen. I am rather stumped, as we appear to have ruled out problems with the pressure switches and relays. If I understand correctly, in jumping (bypassing) the pressure switches at the harness connectors, the pressure switches themselves are removed from the picture so they can't be the problem. Similarly, taking two known good relays and replacing the ones that the schematics say are involved didn't solve anything, either. I haven't checked the pins behind the relays for power and need to do that. There are no other power issues to the FRB or RRB, and the led lights on the relays and fuses are illuminated. I went back to every fuse that I can find in front and back an additional time and can't find any that are not intact and all appear to conduct. For the 'high probability' fuses (relays, pressure switches, etc) I have swapped fuses around and everything works so I don't think the problem is a fuse of which I am aware. There could be one blown somewhere that I don't know where to look? The next place I can think of to look is towards the Smart Wheel end of things. The schematic does show that the turn signal switch is included in the circuitry for the brake lights. There is a single 5 amp fuse on the bottom of the Smart Wheel box in the FRB and it is ok. I'm wondering if a connector could have come loose between the FRB and the steering wheel? I haven't done much in the dash area other than look, so tomorrow is likely a day to see if I can isolate wiring there. Thanks again to all who have responded. I will keep posting any progress or findings. John Link to comment Share on other sites More sharing options...
MyronTruex Posted May 20 Share Posted May 20 (edited) 6. There is power to the 7-blade trailer plug and the toad turn signals work properly as far as energizing the proper blades on the connector. And the emergency flashers work so the bulbs in the tail lights are ok. If the signals are getting to the 7 pin, everything else up front should be ok. I imagine the brake lights and 7 pin plug are in parallel. It sounds like the signal from the rear relays is not getting through a connector nearby. Ignore the following as I talk to myself. Can you feel the relays clicking on and off? If not, use your voltmeter and see if you can find a voltage going on and off using a test light. A meter might not be fast enough. If you find a clicking relay, you also need to check for voltage on the pins of the relay socket. One should have a solid voltage to feed across the relay contacts. That is, you would have either a ground coming and going to the coil, or a 12 volt signal coming and going to energize the relay. Then the contacts of the relay come into play by being a simple on/off switch. But, you already said the toad lights work and the emergency lights work. So that leaves a connection that is in parallel and likely through a harness that needs some exercise. It may take some brute strength and ignorance to push your way through bundles of wires chasing the open circuit. A signal tracer would really help. Edited May 20 by MyronTruex Link to comment Share on other sites More sharing options...
Yoaks5 Posted May 20 Share Posted May 20 21 hours ago, MyronTruex said: I saw Cannon/Barrel type connectors on a schematic or two but was not able to discern their location well enough to suggest what Youaks5 mentions. That is a great idea and place to look for sure. Some pictures of that aree would really help as well. Attached is a picture of my FRB the J connectors (think that's what they called them) are circled in blue. There is a big round ring that just unscrew and you can pull the plug out. If you have burnt pins once unplugged it will be easy to see. My wires are labeled and the print called out which plug the brake wire ran threw. Link to comment Share on other sites More sharing options...
ziaptrn Posted May 20 Author Share Posted May 20 (edited) Two new pressure switches installed. Still no Brake lights. New finding that may be meaningful to someone: The rear backup signal (when you place the rig in reverse) does not sound. In the electrical schematics on page 4, the backup buzzer is wired through the cyclops backup brake light extension of the circuit, so this makes sense to me but doesn't really enlighten. I have unplugged, examined, and re-connected all of the molex connectors that I can find under the dash land alongside the steering wheel with no change. Nothing visible there that looked problematic. I am going to unscrew J1 Round Plug connector in the Front Run Bay (per Kevin's suggestion above) and see if anything looks amiss there. I am not the greatest at following schematics and am likely not the best guy to trace wiring. I wish I could tell how the circuits should 'flow' and then I'd know more about where to look. When I look at the drawings, I don't know what some of the symbols etc. mean so don't know if power should flow through an area or not, etc. Quick question: On the schematic page 35 of the RRB, what is TS-2? I see where the trailer plug wiring goes through that, but don't know what to look for. There are 2 relays on a circuit board there that have wiring that goes to brake lights. Just wanted to update and see if someone had a brain storm! John Edited May 20 by ziaptrn clarification Link to comment Share on other sites More sharing options...
Solution ziaptrn Posted May 20 Author Solution Share Posted May 20 Houston, We No Longer Have a Problem. Found it. After my last comment, I went again to the RRB and found TS-2, and the relay board adjacent that (apparently) regulates the tow brake lighting. Replaced the single relay on that board (despite the schematic showing 2 relays) and SUCCESS. So now we have 2 new pressure switches in place and a hand ful of new relays, but the happy owners can travel on in jolly fashion. Thanks again to all who helped us think our way through this. Problem. solved, understanding increased incrementally, and heavy sighs of satisfaction and relief all around. John 3 Link to comment Share on other sites More sharing options...
Tom Cherry Posted May 20 Share Posted May 20 1 hour ago, ziaptrn said: Houston, We No Longer Have a Problem. Found it. After my last comment, I went again to the RRB and found TS-2, and the relay board adjacent that (apparently) regulates the tow brake lighting. Replaced the single relay on that board (despite the schematic showing 2 relays) and SUCCESS. So now we have 2 new pressure switches in place and a hand ful of new relays, but the happy owners can travel on in jolly fashion. Thanks again to all who helped us think our way through this. Problem. solved, understanding increased incrementally, and heavy sighs of satisfaction and relief all around. John John, Glad it is resolved. From both a troublshooter's as well as a Moderator's perspective...since you found the print...please post it (downloaded the files from the site and print out just that one) or take a photo of it. It is very difficult, even for those of us that ARE familiar...to a certain extent to follow all the steps. There were several itterations of updates to the upper end's wiring. The 2005 COULD have been what in 2006 or just a left or holdover. Then later on in 2006, there was a major upgrade...but not all units had it. CONFUSING. YES. SO, in the future, please shoot a copy of the area you are working in Thanks for your perseverence. Remember the first rule of troubleshooting....TEST before you replace. BUT the Brake switches have been known to have issues Link to comment Share on other sites More sharing options...
Chargerman Posted May 20 Share Posted May 20 Good job John! Link to comment Share on other sites More sharing options...
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