Axis No 12v power getting to coach

[48in366]

I've been searching the forums all day, hoping to stumble upon an answer. I've also been on the phone with three Thor techs (all great) and worked with two mechanics. We're at a loss. I wrote up a decent description, but it vanished when I tried to hit "submit", so, as briefly as I can...

I had my two 12v house batteries replaced today due to one sustaining damage last week. The damage, a broken post, was to the "second" battery, not the one directly connected to the 100amp breaker, and I suffered no power loss when it happened, surprisingly. I'm guessing, had I tested it, I'd have had half the hours, but I've stayed mostly plugged in while waiting for the replacement batteries to arrive (I'm a little remote right now, so it took a week). After the batteries were replaced, there is no 12v power to the coach. We've tried a TON of things, all the basics are covered - the 2 100amp breakers look fine, the 50amp breaker is getting power, the store/use switch makes the solenoid click the way it is supposed to (describing this as best as I can!).

When I plugged into 20amp shore power, only the microwave clock powered up, which I think means the 12v system wasn't getting the shore power. Couldn't crank the genny, as it had no power to it. During one of the store/use switch tests we were doing to listen to the solenoid, I noticed a red light flicker on one of the fuses in the panel with the converter. A bunch of tests there showed that the 15amp "right" fuse and the two 30amp fuses in the middle of the panel were blown. Replaced those, and they blew when the store/use switch was hit to STORE. Put the switch to USE, replaced the fuses, plugged into shore power, and everything powered up. Unplugged, and no power. So the 20amp power was getting to the 12v system, but the 12v power still isn't. At a campsite now, and the 30amp is powering the system, but there's still no power when unplugged. I haven't tried the store/use switch again, as I really would like heat tonight (temps are dropping up here). I noticed a red light next to the "rear" 15amp fuse, tested the lights in the back of the coach, and nothing. Replaced the fuse, keeping the store/use in "use", and I have light. I don't know if the fuses blow anytime the store/use switch is hit, or if it's just when it's hit to "store". Will test tomorrow.

The Thor techs sent me a number of diagrams/manuals. The battery wiring diagram is the one I've seen on the forums. I have an "extra" wire/cable leading from one of the positives to somewhere inside the coach. That's not on the diagram, and the tech said it must be an aftermarket addition and they cannot help any further as they don't know what it is or where it goes, and could be the problem. I'm the only owner, and haven't added anything. Could that have something to do with the two 30amp fuses on the converter? The Thor tech told me those were spare fuses. But they blow when the use/store switch is hit to "use".

The batteries were swapped out. That's it. I get the feeling the answer is an easy one, if I could just put my finger on it! Either that, or I have had some truly horrendous timing with a major electrical issue showing up at precisely the wrong time. I'll try to include photos of the problem fuses (I haven't checked the whole panel myself yet, these are mechanic reported), and the battery wiring (looks good, other than the mystery wire).

1 = Negative to Negative
2 = Negative to Ground
3 = Positive to 100amp breaker
4 = Positive to Positive (replacement wire/cable)
5 = Positive to WE HAVE NO IDEA WHERE (disappears into the frame at the left rear of the photo - not attached to the 3 cable bundle on the side wall of the battery bay)

[48in366]

Best I can do on photos right now...not sure how to post them from Google Drive.

https://drive.google.com/file/d/1up0...ew?usp=sharing

https://drive.google.com/file/d/1ulT...ew?usp=sharing

[Beau388]

Originally Posted by 48in366

I've been searching the forums all day, hoping to stumble upon an answer. I've also been on the phone with three Thor techs (all great) and worked with two mechanics. We're at a loss. I wrote up a decent description, but it vanished when I tried to hit "submit", so, as briefly as I can...

I had my two 12v house batteries replaced today due to one sustaining damage last week. The damage, a broken post, was to the "second" battery, not the one directly connected to the 100amp breaker, and I suffered no power loss when it happened, surprisingly. I'm guessing, had I tested it, I'd have had half the hours, but I've stayed mostly plugged in while waiting for the replacement batteries to arrive (I'm a little remote right now, so it took a week). After the batteries were replaced, there is no 12v power to the coach. We've tried a TON of things, all the basics are covered - the 2 100amp breakers look fine, the 50amp breaker is getting power, the store/use switch makes the solenoid click the way it is supposed to (describing this as best as I can!).

When I plugged into 20amp shore power, only the microwave clock powered up, which I think means the 12v system wasn't getting the shore power. Couldn't crank the genny, as it had no power to it. During one of the store/use switch tests we were doing to listen to the solenoid, I noticed a red light flicker on one of the fuses in the panel with the converter. A bunch of tests there showed that the 15amp "right" fuse and the two 30amp fuses in the middle of the panel were blown. Replaced those, and they blew when the store/use switch was hit to STORE. Put the switch to USE, replaced the fuses, plugged into shore power, and everything powered up. Unplugged, and no power. So the 20amp power was getting to the 12v system, but the 12v power still isn't. At a campsite now, and the 30amp is powering the system, but there's still no power when unplugged. I haven't tried the store/use switch again, as I really would like heat tonight (temps are dropping up here). I noticed a red light next to the "rear" 15amp fuse, tested the lights in the back of the coach, and nothing. Replaced the fuse, keeping the store/use in "use", and I have light. I don't know if the fuses blow anytime the store/use switch is hit, or if it's just when it's hit to "store". Will test tomorrow.

The Thor techs sent me a number of diagrams/manuals. The battery wiring diagram is the one I've seen on the forums. I have an "extra" wire/cable leading from one of the positives to somewhere inside the coach. That's not on the diagram, and the tech said it must be an aftermarket addition and they cannot help any further as they don't know what it is or where it goes, and could be the problem. I'm the only owner, and haven't added anything. Could that have something to do with the two 30amp fuses on the converter? The Thor tech told me those were spare fuses. But they blow when the use/store switch is hit to "use".

The batteries were swapped out. That's it. I get the feeling the answer is an easy one, if I could just put my finger on it! Either that, or I have had some truly horrendous timing with a major electrical issue showing up at precisely the wrong time. I'll try to include photos of the problem fuses (I haven't checked the whole panel myself yet, these are mechanic reported), and the battery wiring (looks good, other than the mystery wire).

1 = Negative to Negative
2 = Negative to Ground
3 = Positive to 100amp breaker
4 = Positive to Positive (replacement wire/cable)
5 = Positive to WE HAVE NO IDEA WHERE (disappears into the frame at the left rear of the photo - not attached to the 3 cable bundle on the side wall of the battery bay)

The 100 amp breaker is for the generator start and the jacks pump. Some where there is a 50 amp DC circuit breaker near the batteries that supplies power to the fuse panel through the latching relay. That is probably the cable you are missing.

[Trophy1200]

Try disconnecting the mystery cable from the batteries and see what works and what doesn't.

Did you mark each wire before disconnecting or take before and after pictures of the wiring?

As it says on the sticker, those 30A fuses are for reverse polarity connection protection, maybe that extra wire at the batteries is a negative rather than a positive? You need to try and trace where it terminates to be sure.

Good luck.

[48in366]

Originally Posted by Trophy1200

Try disconnecting the mystery cable from the batteries and see what works and what doesn't.

Did you mark each wire before disconnecting or take before and after pictures of the wiring?

As it says on the sticker, those 30A fuses are for reverse polarity connection protection, maybe that extra wire at the batteries is a negative rather than a positive? You need to try and trace where it terminates to be sure.

Good luck.

I take hundreds of photos every day, but, silly enough, trusted the mechanic with the job. I have a few photos of the batteries, but none that show the wire (I may start looking back over 5.5 years of photos to check). The wiring does seem to line up with photos from other Axis owners on this forum.

I read that sticker, too, and mentioned it to the second Thor tech. He's the one that told me those fuses are spares. The way the coach is acting, it certainly could be reversed polarity. A Camping World mechanic wired my new batteries up backwards 5 years ago. That time, the fuses blew when I cranked the engine. I'll focus on the mystery wire. We did remove it for a test, but nothing, anywhere, had power, I don't believe. May need to do that test a little more indepth tomorrow. Thanks for the tips!

[48in366]

Originally Posted by Beau388

The 100 amp breaker is for the generator start and the jacks pump. Some where there is a 50 amp DC circuit breaker near the batteries that supplies power to the fuse panel through the latching relay. That is probably the cable you are missing.

The 50amp circuit breaker is hiding underneath my kitchen sink. The mechanic tested it, and said there was power on both sides. That was while the mystery cable was hooked up, so that makes sense if it's what it is for. Wonder why the cable doesn't show in the Thor diagrams, and why their techs have no idea what it is for. I'll try to wrap my head around the best way to test what it powers in the morning. Thanks!

[16ACE27]

The reverse polarity fuses are not "spares" They protect the converter when people connect the batteries backwards. There's no telling what else fried when that happened.

Coming in after the damage is done I'd have to break out the multimeter and wire tracer and figure out where all cables in the battery bay actually go.

You can't expect Thor techs to fix your problem over the phone when they have no idea what has really happened, but the guy that thinks the reverse polarity fuses are spares needs to get away from the customer help area.

[48in366]

Originally Posted by 16ACE27

The reverse polarity fuses are not "spares" They protect the converter when people connect the batteries backwards. There's no telling what else fried when that happened.

Coming in after the damage is done I'd have to break out the multimeter and wire tracer and figure out where all cables in the battery bay actually go.

You can't expect Thor techs to fix your problem over the phone when they have no idea what has really happened, but the guy that thinks the reverse polarity fuses are spares needs to get away from the customer help area.

The techs all seemed to do great at the commonly needed answers - hitting the use/store switch into the use position probably solves the "my coach has no power" problem 90% of the time. But whatever diagram he had that made him think my 30amp fuses were spares is a definite issue. I was hoping there might be an easy solve to the situation, since the cause is 99% likely to be the battery switch. Once the easy possibilities were tried, and failed, however, I agree that there's little chance the techs can help over the phone. I was relying on the mechanics, but they weren't RV specialists, and these rigs can be a daunting challenge. Then again, it was RV specialists that installed my batteries backwards 5 years ago, and blew those fuses that time. All the comments/suggestions here have my brain turning in much more helpful ways. I don't have much electrcial knowledge - I get the sense I'll be gaining a bunch of experience starting tomorrow!

[Chateau_Nomad]

When you turned the battery disconnect switch to OFF... and fuses blew - that smacks of something is wired backwards. A dead ringer for reversed polarity.

I connected the battery on our trailer backwards a few years ago... ignoring the unusual blue spark when I touched the wires to the post. NOTHING in the trailer worked and about half the fuses were blown. I was in denial that I reversed the battery leads... until I looked.

[JamieGeek]

Some things off the top of my head:

Do you have a voltmeter to check things with?

Is it possible you had two 12V batteries and the replacements are 6V or vice versa? Ok looking at your pics they are 12V batteries and wired in parallel.

Looks to me like 1 & 2 are - and the others are +

Is 4 the mystery wire? I'd disconnect it and try again.

Does 5 go to the + post on the 2nd battery at right?

[Jimbo56]

Would it have anything to do with the breaker under the hood by the chassis battery?

[48in366]

Originally Posted by Jimbo56

Would it have anything to do with the breaker under the hood by the chassis battery?

That's certainly a likely culprit in this situation. I discovered its existence a few years back when my AC and wipers stopped working near Big Bend in Texas. Two hours with a helpful local mechanic, and we finally pulled the ducting back to reveal that breaker. I've checked it, and it isn't tripped, but I should probably see if any power is getting to it...

[48in366]

Originally Posted by JamieGeek

Some things off the top of my head:

Do you have a voltmeter to check things with?

Is it possible you had two 12V batteries and the replacements are 6V or vice versa? Ok looking at your pics they are 12V batteries and wired in parallel.

Looks to me like 1 & 2 are - and the others are +

Is 4 the mystery wire? I'd disconnect it and try again.

Does 5 go to the + post on the 2nd battery at right?

It would have helped if I could have got the photos to show in the post next to the key!

1 = Negative to Negative
2 = Negative to Ground
3 = Positive to 100amp breaker
4 = Positive to Positive (replacement wire/cable)
5 = Positive to WE HAVE NO IDEA WHERE (disappears into the frame at the left rear of the photo - not attached to the 3 cable bundle on the side wall of the battery bay)



Everything looks like it's wired right. Just found my multimeter, and I'm tryin to learn how to use it. Pretty basic measurements right now, so I think I'm doing it right. So far...

Positive lead to positive post, black lead to negative post = 12.88 on each battery.

Positive lead to positive post of one battery, black lead to negative post of the other battery = 12.88 each time.

Connection into the 100amp breaker for the genny reads 12.88. Connection coming out reads the same. If I trip the breaker, I get a 12.00 coming out. *But* the genny isn't cranking. I hit and hold the "stop" button on the control panel inside, and get no reading and no activity.

A very mechanical friend was on the phone with me last night, and we're wondering if the problem lies with the solenoid thingy that clicks when you hit the use/store switch (technical name for this currently eludes me). It's on the right hand side of the battery diagram, before the interior fuse panel. That has two big red wires, one on each side. Currently, I'm attached to shore power. The cable on the right reads 13.69, the cable on the left reads -12.88.

About to try some on/off switching, just need to warm the RV up a little more before I lose the heat again!

[16ACE27]

I added your pic to the post above for ease of reference.

The "thingy" is called a latching relay and is controlled by the USE/STORE switch. Its sole purpose in life is to connect/disconnect the house battery bank from the coach's 12 volt DC buss.

The fact that one side reads 13.69 VDC and the other reads battery bank voltage indicates it is in the OPEN (STORE) position and that your converter appears to be working.

The 100 amp breaker goes to the generator and hydraulic pump for the levelers. There should be a 50 amp breaker that supplies the battery side of the latching relay. It is apparently not tripped and connected as you have battery bank voltage on one side of the latching relay.

[48in366]

Originally Posted by JamieGeek

Some things off the top of my head:

Do you have a voltmeter to check things with?

Is it possible you had two 12V batteries and the replacements are 6V or vice versa? Ok looking at your pics they are 12V batteries and wired in parallel.

Looks to me like 1 & 2 are - and the others are +

Is 4 the mystery wire? I'd disconnect it and try again.

Does 5 go to the + post on the 2nd battery at right?

I think I managed to get the battery schematic attached (although I'm sure you are more than familiar with it!). If my second positive post wasn't hiding under the frame, someone would certainly have pointed this out by now. Surprised the Thor tech didn't realise what was going on. The mystery cable isn't mysterious. It's the one leading to the 50amp breaker/fuse that the diagram has coming off the positive post on the second battery. Since almost every image of Axis batteries I've seen has three attachments to the positive post on the first battery, I'd wager that's how the folks building the coaches decided it was easiest to do. I don't think that wire/cable actually reaches to the second battery's positive post. Hasn't solved my problem, but at least it I have more data.

[JamieGeek]

Originally Posted by 16ACE27

The 100 amp breaker goes to the generator and hydraulic pump for the levelers. There should be a 50 amp breaker that supplies the battery side of the latching relay. It is apparently not tripped and connected as you have battery bank voltage on one side of the latching relay.

We're talking about a 2015 Axis--no hydraulic pump (no levelers).

Originally Posted by 48in366

I think I managed to get the battery schematic attached (although I'm sure you are more than familiar with it!). If my second positive post wasn't hiding under the frame, someone would certainly have pointed this out by now. Surprised the Thor tech didn't realise what was going on. The mystery cable isn't mysterious. It's the one leading to the 50amp breaker/fuse that the diagram has coming off the positive post on the second battery. Since almost every image of Axis batteries I've seen has three attachments to the positive post on the first battery, I'd wager that's how the folks building the coaches decided it was easiest to do. I don't think that wire/cable actually reaches to the second battery's positive post. Hasn't solved my problem, but at least it I have more data.

Since yours is close in time to mine (2014 vs 2015) I think you'll find the latching relay in a black box in the driver's side front outside storage bin (there may also be an "RV Custom Products" circuit board in there controlling the relay).

[48in366]

Originally Posted by JamieGeek

We're talking about a 2015 Axis--no hydraulic pump (no levelers).


Since yours is close in time to mine (2014 vs 2015) I think you'll find the latching relay in a black box in the driver's side front outside storage bin (there may also be an "RV Custom Products" circuit board in there controlling the relay).

I have a box in the driver's side front, but it's for the slide controller. If I'm looking at the right thing - a black box with a white label on top that says RV Custom Products, with two big red wires attached, one with a 5amp fuse inline, then it is probably the easiest thing in the world for me to access - under my bathroom sink, which, in my layout, is in the hallway, halfway down the passenger side of the coach. It makes the clicking sound when I hit the use/store switch.

I've been texting back and forth with my very mechanical friend. We may have it narrowed down. I kept going back to the fact that the generator doesn't have power, despite the 12.88v reading on both sides of the 100amp breaker. He said typical generator install involves running negative back to the battery area. While I can't pinpoint a returning wire in all that sheathing, if there's an issue with the ground at the batteries, that could be causing the generator power issue. I'm trying to match the wires at the back of the 50amp fuse to any coming from the batteries. The colours, of course, are all different from the diagram. I'm about 80% sure that the gauge of the red wire attached to the 50amp matches the gauge of the red wire that's currently the assumed ground. Wish I had a micrometer, which I very well might, but can't put my hands on. It's nigh impossible to get the 50amp out of the wall far enough to measure the wire. My buddy is about to have me do a few tests before I go switching anything around for kicks (or shocks).

[48in366]

Originally Posted by 16ACE27

I added your pic to the post above for ease of reference.

The "thingy" is called a latching relay and is controlled by the USE/STORE switch. Its sole purpose in life is to connect/disconnect the house battery bank from the coach's 12 volt DC buss.

The fact that one side reads 13.69 VDC and the other reads battery bank voltage indicates it is in the OPEN (STORE) position and that your converter appears to be working.

The 100 amp breaker goes to the generator and hydraulic pump for the levelers. There should be a 50 amp breaker that supplies the battery side of the latching relay. It is apparently not tripped and connected as you have battery bank voltage on one side of the latching relay.

Thanks for adding the pic. The reading on the latching relay was 13.69 on one side while plugged in, which I'm assuming is the shore power measurement. The other side was reading *negative* 12.88. Not sure if that makes a difference, or if that's how it is supposed to read. The converter has a green blinking light when I'm on shore power, which is blinking away happily. The red light next to the "rear" 15amp fuse went away once I changed it out.

I've gone back to the beginning - the batteries. Everything is pointing at a reverse connection somewhere. I was taking the mechanics word on what was attached to what. I can visually confirm most of the connections, so it's come down to the *assumed* negative to ground wire (number 2 in the diagram), and what was the mystery wire (#5). I have no wire attached to the positive second post, as in the Thor diagram. So it makes sense that the techs putting the thing together decided to attach both the 100amp wire and the 50amp wire to the positive post on the first battery. Given the lack of clearance to access the second positive post, I understand why. A shame the Thor tech, and his supervisor, didn't pick up on that while I was on the phone. So...Mystery Wire #5 is assumed to go to the 50amp breaker. If Wire 2 and Wire 5 are reversed, I believe every issue is covered. Still testing a few things before I go swapping wires, in case I make the situation even worse. An aside - the colours stated on the diagram seem to be there to add some spice to my life. Most do not correlate. Red is the preferred Thor cable colouring, for almost everything.

[JamieGeek]

Originally Posted by 48in366

Thanks for adding the pic. The reading on the latching relay was 13.69 on one side while plugged in, which I'm assuming is the shore power measurement. The other side was reading *negative* 12.88. Not sure if that makes a difference, or if that's how it is supposed to read. The converter has a green blinking light when I'm on shore power, which is blinking away happily. The red light next to the "rear" 15amp fuse went away once I changed it out.

I've gone back to the beginning - the batteries. Everything is pointing at a reverse connection somewhere. I was taking the mechanics word on what was attached to what. I can visually confirm most of the connections, so it's come down to the *assumed* negative to ground wire (number 2 in the diagram), and what was the mystery wire (#5). I have no wire attached to the positive second post, as in the Thor diagram. So it makes sense that the techs putting the thing together decided to attach both the 100amp wire and the 50amp wire to the positive post on the first battery. Given the lack of clearance to access the second positive post, I understand why. A shame the Thor tech, and his supervisor, didn't pick up on that while I was on the phone. So...Mystery Wire #5 is assumed to go to the 50amp breaker. If Wire 2 and Wire 5 are reversed, I believe every issue is covered. Still testing a few things before I go swapping wires, in case I make the situation even worse. An aside - the colours stated on the diagram seem to be there to add some spice to my life. Most do not correlate. Red is the preferred Thor cable colouring, for almost everything.

When you get -12.88 V what are you using for ground? The same spot as when you get 13.69V? If so then that would strongly hint that something is backwards somewhere.

[48in366]

Originally Posted by JamieGeek

When you get -12.88 V what are you using for ground? The same spot as when you get 13.69V? If so then that would strongly hint that something is backwards somewhere.

Yes, same spot. I have a grounding bar (I'm assuming - a bunch of screws with thin white wires attached) on the RV floor in my water heater cabinet (with the latching relay). I used the same screw as ground for the 13.69 reading on the right, and the -12.88 reading on the left. I'm more and more convinced the mechanic installed the ground wire to the positive and the 50amp wire to the negative. They are both red under the sheathing, and what I now believe to be the 50amp wire barely reaches over to the positive post, but that sounds just about right in RV construction.

I unhooked Wire #2 from the negative post for a few tests. Waiting for my friend to finish lunch before I blindly go any further. I did check the latching relay again, with shore power unhooked and Wire #2 unhooked. The right side now reads 0.00, the left side is jumping all over the place and won't give me a solid reading.