Chassis Battery Switch Not Working 2016 Itasca Solei 38R

[wiz-WO]

TL;DR Symptom: 2016 Itasca Solei 38R diesel pusher. The chassis battery switch doesn't do anything. The coach battery switch works fine.

• Backstory:
  What I've done to try and isolate and fix.
  • I have tried the boost switch, I am connected to shore power, and I ran the generator. I also used a jump pack on the batteries.
  • Current voltage on chassis batteries is ~12.8
  • I have checked and replaced the two fuses on top of the chassis batteries, one 10 amp, one 30 amp.
  • I have checked and replaced a 5 amp fuse in the fuse box below the breakers in the compartment on the driver's side in front of the front wheel.

More backstory. Before the chassis battery problem, my power gear levelers stopped working halfway up. These are hydraulic lift and spring return. The touchpad had the Low Voltage LED light on solid (not blinking). My research indicated that it was most likely that the inline 200-amp fuse had blown. If the light is blinking, then it's an actual low battery situation. This fuse is found in the compartment by the chassis batteries underneath the fuses, and accessed by removing two panels. It is on the bus bar where the battery isolator is.
I thought all I would need to do was replace the fuse and be OK. I replaced the fuse, and it blew again. My research indicated it could be a short, either in the wire from the battery to the motor, or the wire from the controller to the motor. I disconnected everything, replaced the fuse again, and got ready to hook up everything one at a time to see when it popped. I ran out of time that day, so I started over the next morning. That's when I discovered the chassis battery would not enable. I quadruple-checked that I had put everything back like it was. (That said, I must have messed up something trying to fix the levelers.)
I am not getting 12 V to the chassis switch other than the internal light, which comes on when you enable the house batteries. I know there is supposed to be a 5-amp fuse for the chassis battery solenoid. I think this is the 5 amp fuse I checked in the fuse box in front of the left front wheel. I tried to verify that it is getting 12 volts, but didn't. I'm heading out to try again.



I think this is the 5 amp fuse

Battery enabler solenoid

 

[Morich]

This is a common area to give us trouble and one of the big issues is that small space does so many different things that it can get to look like a jungle. So I like to chop it down and only look at the parts I need to check.
I'm not sure I follow all you have said so maybe let me ask a few questions and point out some things that I would check?
When you say the chassis disconnect relay is not working, do you mean not passing power on? this relay can be confusing as it is a special relay that "latches" after we hit the momentary switch. It saves battery by only using while we actually hold the switch and it moves, either open or closed to latch and stay there after we stop using battery by letting go of the switch!
But if we don't get battery to the control wires on the relay, it just stays latches and that can get confusing! We can hit the switch but if this relay doesn't get the power, it just stays open or closed where it last got moved!
So I like to first check it is getting power to pass on and also I want to know it is opening that path or closing it as we move the switch!
Is it not closing/opening or is it just not getting power to pass along?



You had a picture that I snipped and did some markup on to show what I would check.
power comes in from chassis battery on cable with red tape, goes to the relay and if closed on to left in this picture and up to RV as well as left through fuse to jacks? Do you have a blue marked cable on left out of sight in your picture? That should go to the pump for jacks!

We can get that info on sheet 3 of this drawing set:

https://www.winnebago.com/Files/Files/Winnebago/Resources/Diagram/2015/15_wire_186059.pdf

This is where your BIM ( battery isolation manager) solenoid lives and connect coach and chassis batteries together to charge as we drive or boost a weak start battery? If you look at these from the rear toward the front, It is kind of divided down the middle with chassis stuff on left and coach on right.
Note the colors on the drawing should match the red and purple you see?


My first thought would be to make sure both battery supplies are getting down to this area but you really only need to work with the chassis side from what I get of your post?
Does chassis battery show on the right side (RED?) of the left relay? Does it go on through the relay to the left side to feed the chassis items in the RV, like the jacks?
If it get to the left side , does it get through the big fuse to go on to the jacks?

If neither of those are happening, do you hear this relay move/click when you push the switch on/off? Maybe the smaller wires in the center plug are not getting the signal down to this point and you need to check back to the switch, etc?
As a help, there should be small ID labels on those smaller wire that control the relay.
We can get the "from" and "to" of those wires with this chart:

https://www.winnebago.com/Files/Files/Winnebago/Resources/Diagram/electrical_guide.pdf

Maybe enough to get you started on the chase?
Wish you luck and shout back if more info might help. It's not a hard part of the RV but too much at one time can blow our own little fuses!!

 

[Morich]

Further thought? If this relay is a problem and you really need to move the jacks, maybe a fair sized jumper like a 12 gauge from right side to left will bypass this relay for temporary?
But that may be several steps too far down the road until you know what's up!!

 

[wiz-WO]

UPDATE I've added a better reply below
Awesome, lots of info here. I will write a much detailed response tomorrow and take better pictures if needed. For now, I can answer
yes, I have the blue wire coming on the far left.
Yes the red wire in the middle from the battery has 12V.
The purple wire, and the downstream blue wire don't have power.
The fuse in between purple and blue was the original problem which had blown. (Let's table that issue for the moment and get the chassis battery working. Once that is done, I'll explain what happened and what I did and hopefully sort that out) I got the jacks up by opening a valve and manually letting them return up)
I checked with a meter, and I don't find power at the momentary switch next to the door.*
I had already downloaded the diagram and compared it to what I had. (I didn't find the blue wire in the back (left) until I knew it was there from the diagram.
You are correct that the issue is only on the chassis side. House batteries are working correctly. I've read about the latching relay and understand how it works. What I don't understand is the wiring to activate it. I assume that 12V comes from somewhere and goes through the momentary switch and back to the relay to change its state. I've read about a 5V fuse that controls this circuit. Is it the one I circled in the first picture? In the diagram on the back of the fuse cover, it's labeled "IP BATT". I don't think I'm getting 12V to it. I pulled the fuse, and put a meter to both lugs and the other terminal to a screw that I assume is grounded. Tomorrow I'll use a jumper to the frame so I know I'm going to ground with the meter.

*I said I don't have 12V at the momentary switch. I do when the house battery is on, but I'm assuming that's just for the light in the switch

Thank you again!!!!!

 

[wiz-WO]

@Morich My responses are inline below.
This is a common area to give us trouble and one of the big issues is that small space does so many different things that it can get to look like a jungle. So I like to chop it down and only look at the parts I need to check.
I'm not sure I follow all you have said so maybe let me ask a few questions and point out some things that I would check?
* When you say the chassis disconnect relay is not working, do you mean not passing power on? this relay can be confusing as it is a special relay that "latches" after we hit the momentary switch. It saves battery by only using while we actually hold the switch and it moves, either open or closed to latch and stay there after we stop using battery by letting go of the switch!
But if we don't get battery to the control wires on the relay, it just stays latches and that can get confusing! We can hit the switch but if this relay doesn't get the power, it just stays open or closed where it last got moved!
So I like to first check it is getting power to pass on and also I want to know it is opening that path or closing it as we move the switch!

OK when we press the momentary switch in the entry, nothing happens, I’m not getting a click at the relay. When we press the house battery, I get a click, and the coach battery is enabled.


Is it not closing/opening or is it just not getting power to pass along?
It’s not opening (no click) so we have no power. What I don’t yet know is if the problem is upstream. Is 12V passing through the switch and into the relay? Or is the problem that it’s getting 12V but the relay doesn’t activate?



You had a picture that I snipped and did some markup on to show what I would check.
power comes in from chassis battery on cable with red tape, goes to the relay and if closed on to left in this picture and up to RV as well as left through fuse to jacks? Do you have a blue marked cable on left out of sight in your picture? That should go to the pump for jacks!
Yes I do have the blue cable (and purple next to it). As mentioned above it doesn’t get power.




We can get that info on sheet 3 of this drawing set:

https://www.winnebago.com/Files/Files/Winnebago/Resources/Diagram/2015/15_wire_186059.pdf




This is where your BIM ( battery isolation manager) solenoid lives and connect coach and chassis batteries together to charge as we drive or boost a weak start battery? If you look at these from the rear toward the front, It is kind of divided down the middle with chassis stuff on left and coach on right.
Actually on my coach the chassis side is towards the center of coach or far side as I look in at the last compartment door on the drivers side
Note the colors on the drawing should match the red and purple you see?
Yes they do match exactly.

My first thought would be to make sure both battery supplies are getting down to this area but you really only need to work with the chassis side from what I get of your post?
Does chassis battery show on the right side (RED?) of the left relay?
Left on my coach. Both large cables are powered.
Does it go on through the relay to the left side to feed the chassis items in the RV, like the jacks?
☹ no
If it get to the left side , does it get through the big fuse to go on to the jacks?
My original issue was that the fuse was blown. I replaced it, and the replacement also blew. Currently I have a third fuse in, and it’s good, but I assume that’s because it hasn't had current through it.
If neither of those are happening, do you hear this relay move/click when you push the switch on/off?

No click
Maybe the smaller wires in the center plug are not getting the signal down to this point and you need to check back to the switch, etc?
As a help, there should be small ID labels on those smaller wire that control the relay.
We can get the "from" and "to" of those wires with this chart:

https://www.winnebago.com/Files/Files/Winnebago/Resources/Diagram/electrical_guide.pdf
I’ll see if I can sort this out. I haven’t found a diagram showing this wire so don’t know where it gets power.


Maybe enough to get you started on the chase?
Wish you luck and shout back if more info might help. It's not a hard part of the RV but too much at one time can blow our own little fuses!!

 

[wiz-WO]

Update. I pulled out the chassis battery latching relay and tested it. I think I'm doing it right.
I pulled out the relay, and I put 12V + from a jump pack to pin 4 and 12V - to pin 2, and nothing happened (no click). I also put 12V + on 1 and 12V - on 3, and nothing happened (no click)
I have 5 ohms between 4&2 and the same between 3&1. No continuity between A & B (as expected)
Is putting 12V through it showing it's not working, or am I doing it wrong?

 

[wiz-WO]

@Morich, I have an update since my last one. Did you see it?

1. I have swapped the latching relays between chassis and coach, and there was no change in behavior. The coach battery turns on and off, but the chassis battery still won't come on. I also had my wife flip the switch while I was in the back next to them, and there was no click for the chassis battery. So the problem isn't the latching relay.
2. I swapped the disconnect switches at the door, and again no change in behavior. The chassis battery switch worked to flip the house battery, so it's not a bad switch.
   I have been poring over the electrical guide and found this:
   ASW / 14 YEL COACH BATT DISC. THERMISTOR (REF LJ) COACH BATT DISC. SWITCH (COMMON)ASW / 14 YEL COACH BATT DISC. THERMISTOR (REF LJ) COACH BATT DISC. SWITCH (COMMON)
   
   So I assume that means the Battery disconnect thermistor is upstream from the switch. I have no idea where that is, what it looks like, or how to test it.
3. Tomorrow, (rain permitting), I'm going to use my meter and check which wires are "hot" coming into the two disconnect switches to see if they are the same. I think that will tell me if there is an open in the circuit, whether it is upstream or downstream of the switch.
   
   Thank you!
   

 

[Morich]

Sorry about the slow response. Things get lost at times!
I need to do a bit of looking at how that power gets to the relay to move it but first, maybe a thought as it seems to already be passing the power, even if not clicking and moving?

If you have power on the red wire, it then goes to this relay and if that is closed it passes on to the left to first the purple line to go to most of the chassis items.
At the same time, it should go through the big fuse to the jacks!
So if the purple is hot, the fuse should pass it on to the blue at the same time. The purple being hot means the relay is currently closed!
Check that is what you meant and the relay is closed, even if it is not moving /clicking?

If I am following, the problem is that the fuse blows when trying to use the jacks? That seems to say there is too much power going through that fuse and that might likely mean something giving a really solid short to ground on out toward the jacks.
Maybe take a look with the meter on that Blue line before you put the fuse in and see if there is not a ground there?

My head is not fully in the game right now, so see if this idea of a short is one problem that blows the fuse and I will take a look, get my head straight and see if I can find how the switch and relay should work. It sounds like two different problems right now, but it all needs checking!

My big issue has been RAIN! And hear in Texas, I'm not used to dealing with that! ARRRGH!
I get used to dried up and now what to do with all this water??

Bummer! Do you notice the little bit at top left of this drawing that mentions chassis battery lockout relay? I thought to look for info on that. One of the problems we have with the RV after 2010, is that they no longer post the wiring as a schematic drawings for the 12VDC! That leaves us hunting/pecking looking for clues instead of going direct to something that shows wire goes from here to there!
My current question was where and what or how this relay fits into things. I've never chased that before as the relays were seeming to work!
Yours seems a question, so where is that relay and that means I go to the interactive parts drawings.

Parts Catalog

But they are not running this morning! Likely they are doing some sort of update and they will be back at some point but that is a killer for what I hoped to look for info!

Sometimes kind of like an Easter egg hunt when we don't have the drawings? Only today the hunt is canceled due to RAIN???
Will try to look under some other different bush!

EDIT? Note that wire ASW is for the COACH, not chassis side? Likely not the problem for current? Will be looking for something the same for the chassis side and get back if anything shows up!

 

[wiz-WO]

Sorry about the slow response. Things get lost at times!

So below I bolded the question I answer below it in italics.
I need to do a bit of looking at how that power gets to the relay to move it but first, maybe a thought as it seems to already be passing the power, even if not clicking and moving?
If you have power on the red wire, it then goes to this relay and if that is closed it passes on to the left to first the purple line to go to most of the chassis items.
It is not passing the power through, I assume, because it’s not activating/changing state/closing.
At the same time, it should go through the big fuse to the jacks!
So if the purple is hot, the fuse should pass it on to the blue at the same time. The purple being hot means the relay is currently closed!
Check that is what you meant and the relay is closed, even if it is not moving /clicking?
No, it’s not closed so the power is not going through the relay->purple wire isolated stud->fuse->blue wire isolated stud

If I am following, the problem is that the fuse blows when trying to use the jacks? That seems to say there is too much power going through that fuse and that might likely mean something giving a really solid short to ground on out toward the jacks.
Maybe take a look with the meter on that Blue line before you put the fuse in and see if there is not a ground there?
I have checked from the stud to the ground and there was no continuity. I’m going out to test it again and will report back. At the moment my biggest concern is getting chassis battery working again as I can’t start it, which means I can’t even move the coach. It would be impossible to trace wires down under the chassis. With the air bags deflated, it’s sitting about 6 inches from the ground. If I can start it I can drive up on 2x10s to look underneath if I have to.

My head is not fully in the game right now, so see if this idea of a short is one problem that blows the fuse and I will take a look, get my head straight and see if I can find how the switch and relay should work. It sounds like two different problems right now, but it all needs checking!
It is two problems, so maybe focus on getting power back and then moving to the jack's issue.

My big issue has been RAIN! And hear in Texas, I'm not used to dealing with that! ARRRGH!
I get used to dried up and now what to do with all this water??
LOL, at least it's not too hot today! We went to college in Waco (late 70’s). Can’t take that heat now!

Bummer! Do you notice the little bit at top left of this drawing that mentions chassis battery lockout relay?
Interesting!!! I love how Winnebago just hung it out in the sky with no idea where it is or where it’s connected. It SOUNDS like a possible culprit! I’ll see if I can find it.

I thought to look for info on that. One of the problems we have with the RV after 2010, is that they no longer post the wiring as a schematic drawings for the 12VDC! That leaves us hunting/pecking looking for clues instead of going direct to something that shows wire goes from here to there!
Exactly! I’ve spent hours poring over the different schematics trying to sort this out.

My current question was where and what or how this relay fits into things. I've never chased that before as the relays were seeming to work!
Yours seems a question, so where is that relay and that means I go to the interactive parts drawings.
So my last test where I swapped relays with the house battery indicates the relay is not defective, but whatever causes it to change state, is not working.

Parts Catalog

But they are not running this morning! Likely they are doing some sort of update and they will be back at some point but that is a killer for what I hoped to look for info!

Sometimes kind of like an Easter egg hunt when we don't have the drawings? Only today the hunt is canceled due to RAIN???
Will try to look under some other different bush!

EDIT? Note that wire ASW is for the COACH, not chassis side? Likely not the problem for current? Will be looking for something the same for the chassis side and get back if anything shows up!
Where did you see ASW?

 

[wiz-WO]

@Morich Hey, looks like they have a new "improved" parts catalog: Winnebago Cortona Portal

 

[Morich]

We are getting into deep, deep trouble for info!
That new parts doesn't thrill me at all and leaves me totally lost for it as a resource! Maybe I can learn a new system but it may take six months!
Starting with a new program to download? Need a password and know the serial number of the RV?
Not sure that is going to work for me and what I have been doing. And then not knowing if it is going to tell me what is needed? UGH!

So moving on to the real problem! I understand the power is getting to the disconnect relay but not through it! So we need to know which pins on that relays plug do what?
Schematic drawing would be great, but we have none for this 12VDC!
Can you find ID labels stamped near the ends of the small wires in that plug? There should be 2-4 letters at the last of a string of info on the wire.
With that wire ID, we can use a chart that gives the from and to of that wire. We can use that info to build something of our own idea of the wiring plan, possible finding which is battery or ground?

https://www.winnebago.com/Files/Files/Winnebago/Resources/Diagram/electrical_guide.pdf

NOT a good method but it may help?

And that list is also new today as it used to be lacking a few of the first pages but now is different but not better! It now shows a recent date and does include the first pages which had been missing. HOWEVER? It used to be searchable and we could hit ctrl+F
to search for thing like ID if we knew them or what we might want. No longer searchable, so we can't go through 70+ pages and find a term like "chassis battery disconnect"!! Somewhere in that 70 pages, there should be a wire that has an unknown ID but it would tell us where the ends of that wire might be found!
Like now? We may be able to find the id if you dig it out of that bundle on the relay but the idea of having a "decoder chart" is to make life easier!

And that circles back around to your question about wire ASW? You mentioned it in post 7, your item 2! I wanted to point out the ASW was on the coach battery disconnect and you are needing to look at chassis disconnect?

Whew?

 

[wiz-WO]

Good news, I think!!! (fingers crossed) I found and pulled out the relay,


it was on the inside wall of the compartment.

(That's just the socket after I had pulled out the relay.)


I visited YouTube University to learn how to test it. When I put 12 volts across the + & - terminals, it chattered just opening and closing. That is wrong, according to what I saw.
Getting a replacement was a PITA. The Winnebago online dealers wanted $30+ plus shipping. I searched all across the web and found out it's "obsolete" but I found Mouser Electronics, which had an equivalent for $8.09. I added overnight FedEx shipping and ordered three, which cost less than 1 from the dealer! I just have my fingers crossed that this is what was wrong. I'll know by 5:30 tomorrow when FedEx gets here. I may jump across it in the morning to get a quicker answer.

 

[wiz-WO]

I was able to access the parts guide with just the year and model. Once there, it was a royal PITA to navigate. If I didn't have a touch screen PC, I don't think I could have. No explanation or a button to zoom in. The worst is that you can't just click on a part you see in 3D. If you have a door or wall between you and the part you can't select, it. I have to zoom and zoom until I'm "inside" the compartment. Then I can click on it. I have no idea how you're supposed to zoom in, I was able to do it with two fingers on my screen. Also they take a lot of screen real estate for the left bar and top header. If you turn on the parts list, you just have a small window in the middle. Enshitification strikes. Enshittification - Wikipedia

 

[Morich]

Okay, we are getting some info dug out. With a bit of guessing we can get closer. Where you are seeing + and - is likely on the other end but I think I can read the little diagram as a second thought to check?
What I think I see from the drawing is that there is a coil inside to operate the relay when it gets current flowing though the coil.

Are there labels next to the pins on the other end? I would expect there to be pins 85 and 86 as the coil where we would want to put 12V to go through the coil to ground. Which is battery and which is ground is not likely to matter and that would be comingout of the socket when plugged in! I see it as when there is power on 30 and the relay is inactive/sleeping, that power connects to pin 87A. Then when operated that power would connect to 87!
This doesn't look like a latching relay but just kind of normal for small auto use. It may just pass power on to the disconnect relay and THAT relay latches when we turn loose of the disconnect switch??

If you want to test relays a bit, this might get it done. If you have some small jumper clips to connect something like a small 12VDC transformer(wall-wart?) to 85 and 86, you should feel it click. Or if you have power of some type like 12VDC on 30, then it should switch from showing up on 87A to 87 as you connect and disconnect the coil!

That's where it changes what we do by what tools we keep hanging around! Little alligator clips seem to hang out around my house!
But if your old relay is not switching and staying solid switched while the power is on the coil, it seems to say it is defective!
Sounds like progress but it sure would be nice to have some paperwork to back up this story I'm telling!

 

[Morich]

Fully agree with the Wiki idea!
I am in a full blown struggle with that idea as I am now on my second desktop after my old windows ten had to go.
My first move was a mistake as I bought what was called a refurbished desktop from a Wal-Mart reseller. It had great specs and great price. But their definition of refurbished is NOT what I expected. It had some paint blobs on the case to cover dents and dings that had been hammered out but the inside was not redone in any fashion I could explain.
I found the keyboard had been dragging on concrete but that is not a problem but when I got into it much deeper, I began to see a company in New Jersey doing custom graphics was the former owner! Bet that company would die if they knew I have their hard drive and info!
Any way, I'm now on a second new one and struggle to find my way!
Both Google and Microsoft are spamming me but neither wants to do it the way I know how!

 

[wiz-WO]

I used a jump pack to test the relay. The 85, 86, 87, 87a, and 30 are a standard of some type for relays of this type. Why Do Relays Use 30, 85, 86, 87, 87a?

The replacements came today, and it is still dead. I was sure that the issue was that relay. I need to do some tracing. Follow from the battery and back to the latching relay. I need to see where it's losing power. I must have an open somewhere.

 

[Morich]

Looking for tricks to get info that we are missing??? Is there any chance the older system with more mechanical than solid state using the current BIM might be wired near the same? Maybe they kept the same wire ID and is there a chance to use those wire ID to sort out where YOUR control wires to that relay might go?
Weird way to get info and pure guess but do you see ID on the small wires on the plug at top of your relay ?
Thinking that if the problem is that your relay is not moving, a check that it gets the signal might need to be run back to some fuse panel, etc.????
If they kept the same wire ID, would the wiring chart let you get more info on where that signal comes from to get here?

I plucked this info from an 2009 model which was before they cut off the 12VDC wiring schematics! It "looks" pretty much the same as what you have after the change to BIM instead of mode solenoid. chassis on left, coach items on right?https://www.winnebago.com/Files/Files/Winnebago/Resources/Diagram/2009/09_k-ser_wire_166377.pdf sheet 2
See how it seems to match in some ways to the drawing in post 8 above?

Any chance you could match up the wire ID from this to what you have and then go to the ID chart for info on where the other end of a wire might be found to check it?
Or do you see wire ID on those wires at all?

Fishing in a very deep pool of theory and possible nonsense!!

 

[wiz-WO]

Fully agree with the Wiki idea!
---snip...
Any way, I'm now on a second new one and struggle to find my way!
Both Google and Microsoft are spamming me but neither wants to do it the way I know how!

So do you have a working laptop now? I'm a PC pro, so glad to help. I have a low-end HP laptop I rescued from the local recycling center and quickly fixed. It's amazing in our throwaway society that people will just toss an electronic device if it's not doing what they expect. It was only a year old and came with Windows 11. I bought a power adapter for it and figured I'd give it to someone who needs a working PC.

 

[Morich]

It was a Dell desktop that came up with a "inaccessible boot devise" error. I have a grandson who is getting into the fixes and he is pretty excited to see if it is something like a loose connector, etc. or if he gets to dig deeper!
So far, I don't find value in moving to a laptop at this point. We let my wife do that part when we travel and each has her unit which gets most of what I can't find or do on the phone. Kind of loosing motivation to learn lots of things if it is not something of interest!

The buy was one of those things not well thought out before jumping! As the end of Win 10 was coming I found what looked like cheap for a memory overloaded item that was labeled/sold as refurbished but their definition was not what I think of as refurb!

Now the biggest problems on learning the new is finding how to cut the sudden increase of junk and ads I'm getting. No point in trying to get info from HP, Microsoft, or McAfee as they are the main folks doing the spamming and wanting to sell me their service!

 

[Morich]

Okay, so let me check that I'm still following correctly! Correct me if not straight!
You have power to the red cable of the chassis disconnect relay right side. But it doesn't get to the left side. That likely means the relay is latched in open setting! The fuse that blows is a different issue and I would deal with it after getting the relay working.
Like this, correct?

I think both the chassis and coach disconnect relays are the same, so I marked up the better picture of the small drawing for the contacts in the relay. I think it is really the coach relay shown but will be like the chassis that we need to work.

I read this drawing as A and B being the big lugs on each side that we want to have contacts close (engage) or open (disengage). Not sure which is A or B! Just that they need contact through this relay!
And to get them closed or open we have two sets of control leads I marked them as pins 1 (-) and pin 3 as positive for one move and 2 and 4 as the other move. Not sure which is engage and disengage, though!

What type switch did you find at the disconnect switch? I'm guessing it may be double pole, double throw, so that it connects both positive and negative for engage or disengage? If you put a meter for voltage across 1 and 3 of the socket, not the plug on the relay, do you see power as the disconnect switch is pushed? First on one of the sets of wires ( 1+3 or 2=4?)
Just thinking it might seem odd to find it missing on both as they seem to show as two different circuits, but that is a guess! My thought is that we might expect to find one of those two sets to be good and the other set bad. That would explain why it is not making any sound as one switch position is already latched to that but the other doesn't make any noise because it doesn't get the signal!

These two wires, TTY and TTZ are control wires from the disconnect switch to the chassis relay, if I'm following right! One to engage and the other to disengage the relay big contacts. I'm not spotting the negative side but that may be just missing it in 70+ lines to search!
But maybe this is a wire you have and that is where you mention thermister!

But WHERE is thermister?
I will go back to parts and scan to see if it shows up in that list!