Frank McElroy

I had an interesting PCB repair last week that I want to share with the group. A member with a new to him 2007 Signature contacted me to have his Big Boy control board (PCB#6 in RRB) repaired. On the board, a copper trace overheated and separated. In trying to find out why, I asked a bit about the history. The new owner mentioned that the previous owner said he replaced his big boy with a new one that didn't work and that he would wedge the battery boost to stay ON for hours at a time. That bit of information explained everything. The battery boost switch is momentary for a reason. It is designed to be held ON for minutes - not tens of minutes let alone hours. In normal operation, the control circuit board pulses 12 volts to the big boy coil to in effect provide about 8 VDC to hold the coil engaged (Big Boy is NOT a latching battery isolator like the Blue Sea ML-ACR). When you press and hold ON the battery boost, you are providing a full 12VDC to the Big Boy solenoid coil and over time it will overheat, fail AND also burn up PCB#6 in the Rear Run Bay. Since these boards are becoming hard to find in salvage yards, the board was repaired and is now working just fine. A word of caution - please don't hold the battery boost switch ON for more than a few minutes at a time.

Another Kongsberg multiplex system repaired. A few days ago, Chuck sent me his 6 inoperative dash switch modules (1 master and 5 slave modules). It turned out he had a master module that needed a replacement 28 pin MicroPIC and 3 slave modules needed to be reprogrammed. Bench tested and all switches now generate the correct digital code. Repaired modules came through surgery and recovery just fine and are now good as new. They ship out on Monday.

These switches generate and send a digital code on a dedicated J1939 databus going to 2 Kongsberg CCM modules. These CCM modules then power item based on switch digital code input. That's how a chassis multiplex system works. These are NOT just simply a series of switches and internal relays.

Yes early production 2008 model year Dynasty coaches (like mine) had conventional Chassis wiring system with the conventional SmartWheel Control Module. It was mid year production of the 2008 model year coaches that converted over from conventional to the Kongsberg chassis multiplex system.

The +5 VDC "fix" only applies to coaches with a Kongsberg chassis multiplex system. If you actually have a smart wheel controller that means that you don't have a Kongsberg system. If you have a SmartWheel control module and you hear the internal relay click but no voltage on the output wire to the wiper motor, then the relay soldered to the circuit board inside the control module likely has failed.

The site has two display interface versions - desktop and mobile. If using a cell phone, the default will be the mobile version. Mobile versions will take most all the icon options shown in the desktop option and put them in drop down screens that you need to select by pressing the 3 dots or bars in the upper part of the mobile version screen. This gives less clutter in the cell phone mobile device screen. You do have an option on the mobile device screen by clicking on the 3 dots in the upper right and select Desktop. You will then see all the options but the print will be a whole lot smaller on your cell phone screen. For me, the only time I use the desktop version is when I'm maintaining the Files to add a screenshot on new files. Everything else, I do on this site, I use my Android cell phone.

On my android phone that's exactly how I do it. A lot more clicks using the Mobile vs desktop version.

Under full heavy braking you should be hearing the ABS system kick in to prevent wheel lockup but it sounds like after the brakes heat up, you get even less braking. That is not a safe condition and must be repaired before driving the coach. When brake drums get hot, they expand and if the slack adjusters are out of range you get reduced braking. I believe that your coach has automatic slack adjusters but that doesn't mean they are working properly. It's critical to periodically adjust the auto brake adjusters with multiple full brake applications while stopped on level ground with the parking brake off. If the auto slack adjusters are working, brake chamber rod travel distance should come back into spec and give you full braking performance . But you still need to inspect your air brake slack adjusters and be sure brake chamber push rod travel distance is within spec with and without brakes applied. If slack adjusters are out of spec, they need to be adjusted or replaced before the coach can be safely driven. Bendix Automatic Slack Adjuster - SlackAdjust-Chk.pdf

It would be important to know if your 2005 has the Intellitec lighting system with slides operated by pressing keypads connected to Intellitec modules typically located in the bedroom closet cabinet. Assuming your coach does have this system then see pages 103-109 in the attached file. One of those pages will fit the slide configuration of your coach. Then, while holding down the DS slide in keypad, see if the LED light that matches the DS retract solenoid wire lights up. If it doesn't, check the associated fuse. Likely you'll find the wire on Module A. It's important to know if the HWH slide relay control box is getting the proper signal to activate the slide retract solenoid. If you do see a green LED light, then check the wiring on the slide solenoid valves located under the removable bin under the second interior step inside the coach.

No problems in viewing HEIC on my android cell phone or windows 10 laptop. I do keep up with software updates including the optional ones.

15-J1 -5 means Printed Circuit Board (PCB) number 15 in the Front Run Bay (FRB), connector J1 on that PCB and wire #5 on that J1 connector. Then check the large J2 pin 5 on the side wall connector on the FRB. There are many times where this multi pin cable connection on the side of the FRB has pin corrosion.

You're not the first to be surprised by all those lights. Often when trying to help someone troubleshoot a problem, I'll ask them to take a picture (with the ignition ON) of a certain board as they press and release a switch inside the coach. That pretty much would tell me what has failed without voltage readings. I'm glad those Intellitec boards were basically designed with self diagnostic LEDs on them.

Those are indicator LED lights that are only powered when the ignition key is on. The color means nothing special. Monaco used alternating colors to make it a bit easier to see which LED went with which description and to add to the "WOW" factor when opening up those boxes. For someone troubleshooting a circuit, the LEDs would show if the circuit and switches inside the coach are working without needing a voltmeter. If the LED is lit, the fuse is good and circuit is getting power. Same for when a switch is activated, a LED light will come on showing that the switch is being pressed. If a relay is supposed to energize, there will be a LED light on the relay coil and another LED on the output wire. So if you know how to read a schematic, you can troubleshoot a circuit by just looking at which LEDs light up. All those LEDs are shown in the wiring diagram board schematics.

I thought it would be good to provide a bit more background. One of the previous owners had a problem with the generator start master switch module. That meant that this master and 5 other slave switch modules plugged into it didn't work. In an attempt to fix the problem either a previous owner or a service center cut open the original switch modules, threw away the multiplex circuit board inside along with the front rocker switch covers. Then they cut out the rest of the plastic interior so they could fit in 3 standard Carling switches. They did this to the master and all 5 slave switch modules. Then they did an attempt to hard wire most but not all the switch function without fuse protection that the CCM provided. Yes, a mess. But the new owner has the skill set to put the wiring back to OEM as long as he can find a master switch module. Maybe there is someone out there with a spare master module working or not and would be willing to sell it to the new owner.

Its is very likely that the relay controlling the AC is bad. These relays aren't FLA relays designed to switch power to the AC units. They were supposed to be controlling the low voltage input from the thermostat. But that's not how Monaco wired them. That's why we see a lot of folks posting that their board has failed. Honestly, the power management system is a nice convenience but if you know your shore power output and what high draw units you have on the same circuit, you can manually do the same thing that the EMS does automatically. Now, if you want to repair your bad circuit board, I'd first measure the resistance between the power pins and the relay contacts and the relay coil to the controller to be sure the board is good. If you hear the relay clicking but no power output to the AC then you know that the control circuit is good. On the top of the relay, you'll find a part number. A google search will likely get a hit. There are a few good electronic supply houses where you'll likely find a direct replacement. I like Mouser and DigiKey. There are other good ones out there too. The rest will depend on your soldering skills. If you don't have a hot air soldering station, you'll need to first remove the solder from all relay pin connections with a solder sucker or braided copper solder removal wick. Alternatively, most local computer repair shops would likely remove and replace the relay for you.

This is a bit of an unusual repair story so I thought I'd share it. Received a private message from a member with a 2007 Dynasty that the windshield passenger side shade would go up but not down. The driver's side shade worked just fine. He correctly diagnosed the problem as being an issue with the Intellitec PCB #11 in the front run bay. Not being able to find a replacement at a salvage yard, he sent it to me for repair. I initially thought it was a failed relay but nope, a corroded trace on the PCB was the problem. I fixed the board by adding a wire to the back side. This is the first time in a long time that I found a problem to be a bad trace on one of the PCB's in the FRB. This is a good example of making sure power is getting to the relay before just assuming that you have a bad relay. 38040029 (Schematic, FRB Board 11).pdf

Likely your 2004 will have 2 ping tanks on the steer axle air bags. One on the DS and one on the PS with each tank feeding the two airbags on each site. Air is fed to the ping tank from the ride height valve or from your HWH / Valid Power Gear systems in travel/level/manual mode. The purpose of these ping tanks is to add air volume to the airbag system. This helps soften the ride up front. Signature models also have ping tanks on the drive axle air bags. Dynasty models don't have ping tanks on the drive axle air bags.

Keep in mind that most of the braking on these coaches is not like cars. Your primary braking is on your drive axle. That's where your weight and braking is located. What's important is to be sure your manual and automatic slack adjusters are properly serviced and you descend downhill in the correct gear and correct engine brake configuration. Changing steer axle from drum to disk would not be on my to-do list for your coach. Learning how to drive down hill or buying a coach with a Jake brake and disk drive axle brakes would be.

Yes, that is very common for motorhome use. The idea is that the useful life in terms of miles driven for a motorhome is no where near that of a commercial truck so the axle ratings were uprated giving a cost savings to motorhome manufacturers. Parts should be referenced to the actual manufacturer label on the axle.

The male fitting is for the tow truck driver to supply air to the WET air tank on the coach to release the parking brakes and provide air for the air suspension system. The female fitting supplies air from the DRY air tank to air up your tires. I have seen cases where a previous owner changes out the male fitting to a female fitting to air up tires from the WET air tank not realizing how the system was actually designed.

Yes, your Dynasty does have two ping tanks on the steer axle. Over the years, I seen a few reports where one of the 4 large diameter braided hoses going between the air bag and the ping tank develops a leak. Finding the leak requires spraying lots on bubble soap on those hoses. When looking for leaks, these flexible braided hoses are easy to overlook.

Thank you - I'll add this to the next parts list update.

Great informative video. I always cut open my filters every time I change them. The Onan fuel filter is a bit unique. There are two stages inside that rectangular case. In the attached picture, the upper portion shows both the front and back side of the long pleated primary filter media. The lower filter shows both the front and back side of the internal secondary filter. So basically this Onan fuel filters is two filters inside the same housing. In case you are wondering, there was about 1,000 hours on this fuel filter. After cutting open engine fuel filters and finding almost no deposits on the primary and basically none in the secondary filter, I let the generator fuel filter run longer. Anyway, that's been my experience but by coach sites inside a humidity controlled garage when not being used.

Thank you for posting this solution. The basic backbone of the Kongsberg chassis multiplex system is good as long as you have good J1939 databus communication. The weak points are 1) the MOSFET from the front CCM that feeds 5vdc to the smart wheel keypads (there is an aux 5vdc supply fix for that issue) and 2) the obsolete Eaton dash switch modules that can now be repaired and reprogrammed if you can't find a replacement in a salvage yard. Unless hit by lightning, CCM modules rarely fail. It's absolutely critical that on Kongsberg chassis multiplex coaches you don't let your house batteries go dead slowly while being stored or sitting at a repair shop and not plugged in. It that happens you run the risk of burning out one or both master dash switch modules. If you lose a master switch module, about half of your other switch modules connected to it won't work.

Thank you for posting the solution. This information will help others. Glad I was able to help.