Boost switch on 08 Knight.

[JimM68]

I've been suspecting this doesn't work, and pretty well proved it the last time I got the coach from storage. Chassis battery was dead, and the boost switch did noithing at all. House battery was good, so fired up the genny no problem. Didn't feel like waiting for the BIRD to kick in (it does work for sure) so plugged my home battery charger to the 115ac from the genny and got enough into the chassis battery to start the diesel pretty quickly.

Anyway...

All the battery's are in a pass side compartment rear compartment.
The boost switch is on the dash, forty some feet away.
Any tips or tricks to troubleshoot this thing?
Does the BIRD have it's own relay then? Cause that does work.

[JimM68]

A quick check has revealed:
Right now both battery banks read 13.24 volts. The rig is plugged in and charging. There is only 1 relay in the battery compartment, clearly wired to connect the positive sides of the 2 battery banks together. It is a Trombette 114-1211 and labelled 12v continuous. It is hot, therefore it is engergized.

I'm assuming now that this coach has a sensor circuit that energizes the relay, and most likely the boost switch goes into that circuit... drats. never easy...

[JimM68]

well, my wiring diagrams are of little help. And I don't seem real clear on how this is supposed to operate either.
I unplugged the shore power cord. The relay stayed energized.
I turned the disconnect for the chassis battery's, the relay stayed energized and I still had chassis power.
I turned the disconnect for the house battery's, the relay dropped out and everything went dead.

I turned both disconnects back on, and about 30 seconds later, the relay energized!!

I turned em both off, then just turned on the house side. The relay energized then dropped out about 6 times, and has now stabilized as off. The chassis side of threr coach is dead.

Nothing happens when I hit the boost button. It's too far away for me to hear the relay, but the step cover and power visors and stuff don't work. Is this an adequate test or am I missing something? Or does the whole thing go out the window if the battery bank flat ain't there?

Anyone with a later model monaco know this circuit?

Note the early Monaco's aren't wired like mine.

[JimM68]

Here's a couple pictures.

Unfortunately, that box with a circuit board in it right about the boost solenoid is unrelated. It contains relays for slide controls and such. The white and purple control wires from the boost solenoid DO NOT even go into that box. They go into the harness and disappear into the bowels of the coach. I cannot locate any of this in my diagrams and am not sure where to go next. I suppose I could attempt to eyeball the backside of the dash switch, but I'm not real high on that, wire fell off the switch would just be "2 easy".

Who knows where to find the control board for the BIRD Relay on an 08 Knight?

[JimM68]

So I pulled the switch panel out of the dash, not much to be seen there. all the wires are connected. and they are all white.

Pulled an access panel on the side below the dash, the wires from that switch panel go there and connect to a harness with colored wires at least.

Went to the drivers side front basement compartment. Big fuse panel there. Need to get my reading glasses and study on that some. I do see the isolator control circuit board there, so I might be on the right track...

Any info on this circuitry would be greatly appreciated!!!

The next time I hafta go inside I'm gonna needa turn on some power and get some A/C going, it is way hot in there!

[JimM68]

Any Monaco wiring guys out there?
I'm starting to scare myself...

My wiring diagram, plus searches which hit a number of older posts here... is telling me that the boost fuse F55 on the panel in the front drivers side compartment...

Leaves on pin 6 of C409... heading to the dah to power the boost switch and thge antenna booster (which also doesn't work.)

That connection on my coach is EMPTY.
I've verified the pin has 12 volts, and the 12 volts leaves if I remove that fuse.
There is a purple wire in the connector right next to that pin, and it has no power on it at all...

The guide on the panel cover shows pin 6 is the boost connection and pin3 is a SPARE.
The purple wire is on pin3, pin6 is has no wire.

[YC1]

You have learned a lot and I might be able to help you wrap your mind around it. Mine was confusing the heck out of me at first too. Since you have the BIRD system I should be able to provide you with schematics and pictures of my setup if that helps. However you have most of it already.

I bet you have solar panels. If so then the BIRD was reading that as a CHARGE voltage and energizing the Trombetta just as it should.

If you are not connected to solar, no shoreline, no generator or any other charge source like the engine running then you would hear the Trombetta pull in by pressing the aux start button.

As you mentioned the relay can get so hot it will burn you. Poor design to have a relay draw almost 1.5 amps but not totally uncommon.

These relays are an absolute known issue for getting gunked up inside. If I was not an ET with lots of experience it would have gone unnoticed for me. My new 08 HR Endeavor had strange battery charge issue from the start. I compounded the troubleshooting process by adding solar panels that charge both banks. I was unfamiliar with the BIRD operation and it can add more questions than answers. Especially having a delay time in it.

I believe I have the link for the factory description of how the Bird works and will include it in my following post.

I will also include a picture of a defective relay.

What I found on mine was 1/2 of a volt difference on each large terminal of the relay. There should not be any voltage drop across a switch. After replacing the relay I drilled out the four rivets holding it together. It was green and gooey inside. The contact were a mess. I took it apart and cleaned it up shiny and new. A bit of wd40 for good measure and some small nuts and bolts put it back together again to keep as a spare. If anyone needed to in an emergency you can simply stack the large wires on each side onto one side and your batteries will get charged. You could shut off the battery disconnect on the engine side if you wanted to isolate them again for a few days if you were boondocking.

[Monacoach]

Jim if your boost switch is not working it stands to reason ( in my mind) that your isolator relay is not working. On my 08 HR their are two items, one in the front left bay and one in the battery compartment being a solenoid. It looks to be to the left of your batteries. Anyhow.. I would ask,,, when disconnected ( not just the first few minutes) but after driving for a bit are the house batteries getting charged? It could be a bad Isolator relay solenoid and/or the circuit up front that sends the signal... oh ya I forgot.... on ours there is a small fuse that operates both the Booster switch and the antenna booster.

[JimM68]

OK, the boost button is working .

What I found is, the schematics showed F55 (5 amps) providing 12 volts to the dash boost switch thru pin 6 of C409. But the fuse was good, yet no power to the switch.
And no wire on pin 6 of C409.

Reality turns out to be F56 (15 amp) labelled as a spare on my panel and on the schematics, The purple wire was on pin 3 of C409, connected to F56... which was blown.

So now, the solenoid clicks when I hit the boost switch!! Yea!
Unfortunately, I'm still not getting any power to the chassis side of the coach.
It's hard to "fake" a dead battery.

[YC1]

Defective solenoid.

I cannot efficiently figure a way to attach pdf files. If you know how I will send them to the group otherwise you can e-mail me and I will gladly attach several great PDF files I have on the issue.

Note: You can take the large nuts off the terminals and press the contacts out for easy cleaning.

[JimM68]

Here's the photographic proof...
schematic and coach "fuse guide" both showing F55 for the boost and F56 not used.
And a shot of the coaches fuse panel. Fuse in F56, none in f55. Wire in pin 3 not pin 6, and the boost switch works.

[moisheh]

Jim:

You win the award for the most posts answered by the OP. You are obviously much smarter that you think as you are the one that solved the problem. 3 stars!!!

[JimM68]

LMAO Moisheh!!!

You coulda chimed in sooner and saved me some work?
And the jobs not really done. Still don't know what blew the fuse...
And won't know till I let the battery's run down if the relay actually works.
It does click now though.

[YC1]

Quote:

Originally Posted by JimM68 LMAO Moisheh!!! You coulda chimed in sooner and saved me some work? And the jobs not really done. Still don't know what blew the fuse... And won't know till I let the battery's run down if the relay actually works. It does click now though.

Measure each battery bank without the relay closed. You can pull either small wire off the relay to be sure it is not engaged. Now engage the solenoid. You should immediately see the same voltage on each side of the large terminals. If not the solenoid is resistive and needs to be repaired or replaced. If you see any voltage drop at all the solenoid is defective. The solenoid could easily be intermittent as well. For $30 I would replace it in a heartbeat because of the track record of the component.