No House 12v but Inverter Works Fine

[Gormleys]

Help!

I just went out to my 2015 Forza 34T and there were no lights on even though the MH is plugged in to 50 amp shore power. A/C appears to be working fine, but no 12v DC. The Inverter shows "float" and taking a volt meter to the batteries, they show 13.6v DC. Turning off shore power, the inverter provides A/C and the refrigerator works. All DC circuit breakers appear to be in, but the "House Battery Disconnect" switch is lit and I cannot turn it off. When I try to turn it off, the solenoid show "click", but nothing happens.

I think it may be a bad solenoid. Anyone know where it is located and how I can check it?

What else should I check to get 12v DC working again?

[Morich]

Lots of info to pass along and some you may/may not know but I will try to pass info along and let you decide what you may need? No offence intended, just easier to get the info across in one post ---if we can!

Location of solenoid is in first couple pictures that I snipped from the parts catalog here:
https://catalog3d.winnebagoind.com/menu/Parts.htm

Not knowing, I chose the early build date but likely not changed on later year change.
Click the pictures to get larger/better view.

The first pic is from left side showing a panel near the rear, opposite the batteries.
Second pic is as if we turned the RV and look "through" at the back of that panel to see the solenoid.

For wiring they have been cutting back a bit on the wiring info and they are not showing much on your battery disconnect wiring, but I did mark out what I see as the way the mode solenoid works.

Left side of the drawing shows both coach and chassis batteries with wires going to the solenoid, chassis connected to left side on drawing and marked in red and coach going to big post on right and marked in green.
The blue marking is what I see as wiring coming down from the dash switch to the solenoid with coil inside and then on to the ground on the other wire marked in blue. This is what makes the electromagnet in the coil pull the contacts closed to connect red to green!

I get the wiring info/ ID from this chart and the wires labeled on the drawing (LR and MG)
https://www.winnebago.com/Files/File...ical_guide.pdf

Sad part is that they show us the two disconnect relays on the drawing but NO WIRES! We know they are there but how they work and how they are wired is not known! OUCH?

Maybe if you can get into it far enough, you can search out which disconnect switch works which relay and maybe see some ideas on them?

About all I can see, so good luck and happy hunting!

[Gormleys]

Thanks! This will definitely give me a great starting point. I will provide updates as I get into it.

[Gormleys]

Thanks Morich for providing the detailed drawings and links to the Winnie parts lists. I will definitely use them in the future.

I did locate both the battery isolation manager solenoid and the battery disconnect relay based on these. For reference, they were mounted ninety degrees off from how they showed on the 3-D drawings. That puts the coach relay way deep in the bay and really hard to access.

But luckily, when I turned on the coach engine to move it so I could open the bay doors further, the lights came on under alternator power. So the disconnect relay was fine and actually doing its job. I have four 6v batteries and it turns out that #3 was only reading 3.4v instead of 6.3v like the other three. Turns out I have had a bad battery. Everything came back up normal when I replaced it.

Moral of the story, always start by checking the voltage of ALL of the batteries and not just one set.

[Morich]

Good deal, glad to hear it is working for you. In a way I was feeling a bit guilty as I had meant to get back to you with a much better thought on testing the mode solenoid---but then I got involved with a major crisis in the ice storm in Texas and lost my power and water, internet and most of the things we call progress! Things like being able to flush the toilet became real obsessions for a while. Back to somewhat level now, though.

So if a person was wanting to test the solenoid and found it is way back out of reach, the better choice is to test the operation from the batteries instead of digging to get hands on the solenoid just to test.

Keeping in mind that the solenoid only does one thing, connect the two battery strings together, we can check the battery voltages.

The two strings will almost always be slightly different voltages so if we test the voltage on start and coach and they are a bit different, then we either start the RV engine so the engine alternator is supposed to charge the coach battery, we will expect both the start and coach battery voltages to suddenly jump up! The alternator on a vehicle will often put out as high as 14+ volts, so if we see that voltage get to both sets of battery, we know it is the mode solenoid doing it's job!
IF on the other hand, we see that higher voltage get to the start battery but not the coach , then we might have to say the mode solenoid did not connect them and want to look further----even if that means digging into the internals of our RV!
Happy travels and there are always new things to figure out!!

[powercat_ras]

On my 2015 Vista 27N I was able to go back to 2013 and download the complete low voltage wiring diagram for that model year Vista, 2012 was the last year Winnebago posted full low voltage wiring diagrams, for 2013 models. This is pretty close to my 2015 Vista, just missing a couple of things that were introduced after 2013 models.

So you might go back and see if you can get the full wiring diagram for a 2013 Forza to aid you.

Not sure how much this will help since it's for a Vista but it may give insight into the method of operation of the Winnebago coach disconnect contactor and the switch that controls it, at least on 2013-2015 Vistas.

If like my 2015 Vista, the coach battery disconnect switch is a center off double pole double throw switch that is fed coach battery thru a 5 amp in-line fuse located in the chassis electrical box behind the breaker panel and chassis ground thru wires marked LG and KF (KF appears to just provide a ground return for the LED in the switch)
.
Wires LJ and LH go from the switch to the coach battery disconnect contactor and 12 volt is applied to LJ or LH by the normally center off switch to move the solenoid driven contactor to one position or the other (connected or disconnected). There's no voltage across the solenoid when the switch is in the center off position. There's two white wires marked FM connected to chassis ground on the solenoid on the Vista.

The LED in the switch is a separate wire that in my Vista is off a fuse (not a circuit breaker) in the 12 volt fuse panel that is part of my WFCO power box, in my Vista the wire is off 15 amp branch circuit GC. That LED can light even if the contactor is off, if the RV has AC power and the converter-charger is working and the fuse for the GC circuit (in my Vista, anyway) is not blown.

The chassis disconnect switch is a similar method of operation BUT is slightly more complicated because there is a lockout relay (also behind the breakers in the chassis electrical box) in series with the 12 volt feed to the switch, to make sure it's impossible to hit the switch and kill chassis power when the ignition key is in the ON position.

[Morich]

That's where we "may" find some value in checking prior years but it also has to go with knowing that things may not be correct as I've looked at my wiring and tried to go back and found it just goes so far off that I'm not getting much info to try trusting.

On my look at the "next closest" drawings, I see a chassis battery disconnect which has been dropped on my year/model, making some real changes in the way things will work.

So far, I have not had to get hands on or do any solenoid work on the current RV as it is stuck back where it requires removing a panel that is screwed on in a really tough way to get the cover off. I had to modify my offset screwdriver to make it short enough to the cover screw out and then when I got that far I was still looking at removing the breaker panel to even get a good look at the solenoid!
After spending an hour to get the cover off, I decided it could wait to have a real problem before I worked on getting closer. Just kind of lost interest in looking!

That was part of figuring out that I could "test" the solenoid operation at the batteries and not really get to the solenoid body itself.