2008 Monaco Big Boy Solenoid problems

[birdshill123]

We did not use our unit during the pandemic. It was in storage . When the border opened we left for Mexico without doing some required repairs. While in Mexico health issues prevented me from repairing an issue with battery charging. But without the  generator Alladin was showing a discharge on the house batteries. Usually around 20 amps. I knew the Bigboy relay needed attention. I  replaced the relay about 9 years ago . I rebuilt the spare and installed yesterday. Same problem but the discharge is 6 amps. I let the engine run for around 15 minutes and nothing changed. Voltage on both sides of the big boy . Voltage at the 2 small relays. On the 08  Dynasty Monaco used an electronic board to control the charging. It is an Intellitec "B.I.R.D but an open board. Before I replaced the original Bigboy years ago I installed a new board. I did some checking yesterday and here is what I found.

Engine running: chassis batteries 13.8 volt on Alladin, House batteries 12.5 volts 6 amp discharge. 

If I hit the battery boost the house batteries show a charge of  about 35 amps

The Intellitec board shows the following:

Green light marked " battery disconnect on" is not lit

Green light marked  "battery disconnect off" is not lit

Green light marked "Iso relay on" is not lit

Red light marked " 7.5 amp pcb power" is lit

Red light marked "7.5 amp  battery dom" is lit

At the bottom of the board  there are 2 lights

The yellow light  marked " Battery disconnect switch"  is not lit

The green light is marked on the circuit board.  States" ISOL lockout". It is lit. 

I have the original Intellitec board. It may be OK  .

I have not tried replacing the board but wonder if something else is causing my problem. Any help appreciated.

 

Thanks

[Frank McElroy]

It sounds like big boy is not engaging or if it is, the contacts are bad.  Is big boy humming and hot?  If so, the internal contacts are bad.  If big boy is not engaging, check to be sure both battery cutoff switches are turned on.  If either one of them is turned off, the sensor wire on these switches will prevent big boy from engaging.

[birdshill123]

Thanks Frank. The big boy contacts are clean. I tested it before installing. Voltage on both side.  I will check it with engine running. Both battery switches are on. I will do some checking again. Does the Bigboy come into play when running on shore power or genset? The problem only exists while the engine is running. No 110 connection.  But hitting the battery boost  charges the house batteries.

[Frank McElroy]

Since the iso relay on light is not lit, it means that the circuit board has NOT called for big boy to engage.  There are a few reasons for that to happen.  First, the engine batteries must be above a certain voltage and 13.8 volts should be enough with the engine running.  Then there is a few minute time delay.  With the engine running, the iso relay light should turn green when big boy engages to charge the house batteries from the engine alternator.

Since ISO Lockout led is lit, it confirms that both battery switches are turned on.

Do you hear big boy humming and see the chassis batteries being charged while on shore or generator power and the inverter charger turn on?

[MyronTruex]

Using the battery boost button indicates the solenoid is indeed working fine. Or fine enough for now. 

It is always easy to tell if the big boy is being engaged by measuring the voltage across the small terminals. Depending on how it is driven, it may be full battery voltage near 13 or so. Or if driven by a fancy board that sounds like you have, it may be driven by pulses once the relay is engaged. The voltage shown on a voltmeter will be closer to the 6-volt range in that case and as suggested, you may hear it humming due to the pulses.

If you could post some pictures or a link to a schematic for the device it should be easy enough to sort out. 

IF you have a spare board, put it in. Substitution is often the easiest way to sort things out.

[Frank McElroy]

50 minutes ago, myrontruex said:

Using the battery boost button indicates the solenoid is indeed working fine. Or fine enough for now. 

It is always easy to tell if the big boy is being engaged by measuring the voltage across the small terminals. Depending on how it is driven, it may be full battery voltage near 13 or so. Or if driven by a fancy board that sounds like you have, it may be driven by pulses once the relay is engaged. The voltage shown on a voltmeter will be closer to the 6-volt range in that case and as suggested, you may hear it humming due to the pulses.

If you could post some pictures or a link to a schematic for the device it should be easy enough to sort out. 

IF you have a spare board, put it in. Substitution is often the easiest way to sort things out.

The wiring diagram is in our downloads under 2008 Dynasty and it is RRB board #6.

Engaging battery boost only confirms that big boy will engage but doesn't mean the the PIC circuit is actually working to decide when big boy engages and disengages depending on battery voltage.

If the OP waited long enough (at least 5 minutes) and the ISO relay on light doesn't turn on, then I'd swap out the circuit board.

Based on the original post, we know that the board is seeing both house and battery voltages, the sensing circuit confirming both battery cutoff switches are closed, and the battery boost switch will engage big boy.  About the only thing left is a failure of the PIC circuit section of the control board.

[birdshill123]

6 hours ago I started working on the problem. Checked  the Big Boy  and checked the small relays. Everything seemed ok but still discharging. Finally decided to replace the B.I.R.D b board. It is in the rear run bay and tucked away almost  behind the tail light. I remembered when I replaced that board. I am working outside and the mosquitoes are having a feast. I removed the board but the install is tricky. I have magnetic socket bits in my shop in Mexico but here I had to use masking tape to hold those tiny machine screws. I had to unplug the engine board just above the Intellitec board. The engine would not start and gave me a com failure. Removed and reinstalled the connector and fired up the Dynasty.. WOW. it is charging!! I can even hear the Big Boy humming! pic is attached showing the break in the board. It could be  repaired. M& M wanted $420.00 plus shipping to repair! I am sure glad I bought that board when Northwest was selling them for about $100.00. Thanks for all the help

[MyronTruex]

Oh heck, that is a ten minute repair if nothing else is bad on the board. 

Scratch it clean and cut a resistor lead off to solder in place. Of course everyone carries a bag of resistors. So a piece of wire pulled from some scrap will do fine. 

I would love a picture of the other side too.

You might want to take a voltage measurement across the small terminals now that things are working for future reference. 

M&M may be very familiar with a common failure on this board and it might require a few more components to repair it. Since you can see the issue you may be able to negotiate a much smaller charge. They would be able to test it and if the simple fix did not do it they can toss it and charge you maybe 1 hour labor. All things are negotiable. 

[birdshill123]

I should add that I really would like to install the Blue Sea system. However I have not figured out how to get a wire from underneath into the dash area. The carpeting is attached to plywood and covers the bottom of the firewall. Maybe behind the front drawer? I have also not checked to see if there are empty tubes that are supposed to be underneath.

[Frank McElroy]

Wiring Harness - Spare, FRP, Dash, PS Armrest, Bay 2, RRP, Hitch Area.pdf

36 minutes ago, birdshill123 said:

I should add that I really would like to install the Blue Sea system. However I have not figured out how to get a wire from underneath into the dash area. The carpeting is attached to plywood and covers the bottom of the firewall. Maybe behind the front drawer? I have also not checked to see if there are empty tubes that are supposed to be underneath.

On my 08 Dynasty there it a one inch empty PVC tube running on the PS along side the frame rail exiting behind the steer axle and ahead of the drive axle.  There is also an unused wiring harness with ends in the FRB, RRB under dash and in the PS arm rest.  I'll post some pictures.