Loss of 12V Power in Coach

[Gary LS]

This afternoon as I went into our 2009 Monaco Dynasty coach to check things out before our upcoming trip I found that none of the 12v lights or slide operating motors will work. None of the light switches operate nor do they light up when touched....

Immediately suspected the salesman's switch so I opened up the rear run bay and check and there is 13.2v+ on both terminals/sides of the solenoid. Additionally, the Big Boy is functioning correctly in that there is 13.2v on both terminals and it cycles in when I start the generator or the engine.

Next I suspected the transfer switch so I unplugged and plugged in the coach and each time the transfer switch operated. I then cranked the generator and again the transfer switch seemed to operate correctly.

I did start the engine and suddenly everything came on and worked AOK for a few minutes and then all went back off....the engine is charging the batteries at 14.2v and the inverter is charging at 13.8v....so, doesn't seem to be any issue(s) with the charging system.

I do have 120v for the residential fridge, etc. inside the coach.

I opened up the rear Multiplex panel in closet and there are red pilot lights on all panels. Checked and confirmed that there is 13.2v being supplied to each Multiplex panel.

I cycled the battery cutoff switches and no change.

The porch light works AOK and the engine & generator all start and work AOK....just no 12v for lights and systems in the coach.

Any thoughts or suggestions would be appreciated.

Thanks

[WinnieView]

Most likely a bad coach battery.

[twinboat]

If the inverter is charging at 13.8 volts, and you are testing and reading 13.2 volts, something is missing.

I think all of your reading are of chassis battery voltage and your house battery may be deeply discharged.

The lights coming on after start up may have been your BIRD control connecting the chassis battery to the coach battery.
The reason they went back off was because the BIRD control won't allow the chassis battery to drop below 12.6 volts. It will open the Big Boy to prevent alternator overheating.

Check the connections on the house battery and their ground cable. Also check voltage directly on the house battery terminals.

[K7JV]

I don't know if you have the same Intellitec designed system as is in our '06 Dynasty, or not. But you said in the multiplex cabinet you see red pilot lights on all panels.

It is my opinion that this cabinet is where you problem lies. The only systems that you say are not working are those controlled by the multiplex system, and yet you have power to the multiplex modules.

On our Intellitec system, we have LED's at each of the fuses on the FET and Relay module outputs. The only ones that are lit are those that are currently in the switched "ON" state. All others are dark.

Your 120 VAC systems do sound like they are all working properly. And from what you described, I think that most all of your 12 VDC system is good, as well, with the exception of those circuits controlled by your multiplex system.

On our coach the LEDs in the Intellitec cabinet are green when the circuit is energized, not red. So we may have hugely different systems. If so, I'm not going to be of much help other than to suggest that the problem likely could be in that cabinet.

There is probably a three-conductor circuit that leaves that cabinet and daisy-chains thru the switches, and the integrity of the connections for those three conductors would be the first thing I would check. Beyond that, I will defer to someone who has the same multiplex system as yours. (Ours has one CPU module, two FET modules, four latching relay modules and one input module. Like I said, the only lights are for those circuits energized, at the time. On our unit, the CPU and/or the three conductor circuit would be the common denominator in a situation like you are describing.)

[Ivylog]

Originally Posted by Gary LS

This afternoon as I went into our 2009 Monaco Dynasty coach to check things out before our upcoming trip I found that none of the 12v lights or slide operating motors will work.
I did start the engine and suddenly everything came on and worked AOK for a few minutes and then all went back off.
Thanks

I read every post on the multiplex system so hopefully when mine acts up I might have some idea what's going on. I think the above is key to your issue which tells me your house batteries are dead. I would go to them and turn the switch off near the batteries and check the actual voltage of the batteries.

Hopefully once yo figure out why they are not being charged and get them back up to 12V your multiplex system will fix itself...work.

[Gary LS]

First let me say THANKS to everyone that looked at this problem and suggested things to test and check out.....

I spent hours checking fuses, solenoids, etc. and all were OK....yet the Multiplex system just was not passing current through to the various circuits.

As I was walking back to the rear closet to do pull each fuse and check for continuity suddenly there was a "bump" & some noise and all of the circuits came on and all is working perfectly now...…

I had a call in to Mark at M&M Electronics and he called at the very moment I was standing there in the middle of the coach with this puzzled look on my face as I had done NOTHING and suddenly the Multiplex system came back online and all was working AOK. Mark and I had a good laugh that perhaps the system knew he was about to call.....

So, a BIG THANK YOU to everyone that offered suggestions but know that I do not know what changed but thankfully the system is back up and operating as it is supposed to....

Thanks again!!!!

[K7JV]

Gary, that's great that you've got your power back! I'm attaching two drawings that I made that very basically describe the chassis and the coach battery systems, for our coach, at least. It may be close to what you have, though I'd expect numerous differences. Our Dynasty is an '06. On the coach battery drawing you can see where the only device capable of creating a "bump" sound would be the Battery Cut-Off relay(s). Note that the Intellitec system was fed from RRP 7 (Rear Run Panel lug #7). It would be interesting to know if you had power to the systems on the five fuse boards in the front run panel that was fed from RRP 6 (Rear Run Panel lug #6). That would tell you whether the problem might have been from the single relay on the left, or from the control power to both of the battery cut-off relays.

But you said you had lights in your Intellitec cabinet, which would suggest that the problem is not with the "salesman switch" relay(s). That's just wild! The only other "bump" source I can think of would be one of the loads on the Intellitec system that might have made a sound when power came live from the CPU. All I can say is keep Mark at M&M's phone number where you can find it easily, if you ever need it again.

These may at least give an idea of where things might source from, and how. But I am convinced that there are no two coaches "out there" that are configured and wired alike!

[Gary LS]

Jim, thanks for the info....will check out the things you suggested.

I have a friend in the MH business and he contacted a mobile tech that he recommends that has a lot of multiplex experience and fortunately he is available this morning and is on his way here to try to help me find the problem(s)….so frustrating.

Thanks for your info and time to respond.

[Gary LS]

Thanks for your advice.....after LOTS of checking and testing it turns out that the intermittent problem was being caused by the "blue loop" connector on the CPU of the multiplex....once I disconnect that line all other 12v systems work AOK.... So, we can now continue on our trip using a "work around" solution for the areas having no 12v service until I get a new CPU (that I have ordered) and find someone that can assist with transferring the programming from the ole CPU to the new one.....

Thanks again, gary

[Outbound]

Congrats on finding the problem, that was a hard catch.

[K7JV]

Fantastic! I wonder if the "blue loop" may be what I was calling the three conductor circuit. Anyway, congratulations on finding the issue!!! I'm not sure how you did the work-around, but kudos to you on finding a way to go forward!