12 volt house fuse box

[Huck]

I am hoping someone can help with an issue that just popped up on my coach. I have a 2017 Challenger 37LX that I have been full timing in for over a year and a half. The park we are staying in currently has been having some power issues the last couple of days with it being shut off a few times for maintenance or something. Yesterday when the power shut off all the 12 volt lights were flickering a little bit and I could hear a rhythmic clicking sound. I traced the sound to a 12v 15A relay in the 12 V fuse box under the bed. I removed the relay and the clicking and flickering lights went away. The only thing that doesn’t seem to work now is the lights and fan in the half bath. I tried getting a new relay, but it’s different than the one that was in there and it doesn’t work at all. Does anyone know how to test a relay, and or know why that circuit is a relay and not a fuse like all the other circuits in that box? Also could I just put a 15 amp fuse in there instead of the relay? Thanks for any help you can give me!

[Mr Sunshine]

Looks like you have stumped the forum! You may have to ask those questions to Thor or a trusted RV tech.

Maybe bumping this up will get the right person to notice!

[HaRVey]

Your best bet is to go to a NAPA store or some other place with knowledgeable personnel who can identify a suitable substitute relay. Relays come with different max current ratings (20 or 30 amp, etc.) and different default circuits (i.e.normally open when not energized or normally closed).
There are marking on the case of the relay which show the type of connections and non-energized state of the relay as well as how many current paths it supports. While you could use a larger amperage capable relay, the pattern/symbols must match or it will not function or function correctly.
You should not try to bypass a relay because their purpose is to provide a higher current to the things that they are powering than can be safely sent through the switch (assuming it is a physical lightweight switch with small guage wires.

[Huck]

Attached are some pictures of this relay. As you can see it’s the only one in the box, and as far as I can tell the only thing affected by it being removed is the 12 volt in the half bath and the vent fan in the kitchen. The only things in the half bath that are 12 volt are two lights and the vent fan. No other 12 volt systems have been affected not even the lights and fan in the full bath. I am going to try a 15 amp fuse to see if that does anything. If anyone knows where I can get a relay like this one please let me know. If you can give me a part number I can go with that too. I will probably call Thor tomorrow to see what they say. Thanks for any and all help.

[camperguy99]

That looks like a thermal fuse that is continuing to open and close due to an overload on the circuit.

[Beau388]

Originally Posted by camperguy99

That looks like a thermal fuse that is continuing to open and close due to an overload on the circuit.

Yep, it is an automotive circuit breaker type 1
Type I Automatic Reset, which means the circuit breaker keeps cycling on and off until the overload is removed.

[Huck]

Originally Posted by Beau388

Yep, it is an automotive circuit breaker type 1
Type I Automatic Reset, which means the circuit breaker keeps cycling on and off until the overload is removed.

So, replacing it won’t fix the problem? I wonder what could have happened. It’s worked fine for over a year and a half now of full time living and quit working during a power outage the other day. I do have one of those super fancy surge protectors installed on my rig, so whatever happened had to come from inside.
It wouldn’t surprise me if something just worked it’s way loose as I have had several electrical items not secured properly when this thing was built.
I guess I’ll start with pulling out the fuse box, since it’s not even screwed in...maybe one of those wires is touching something else back there.

[lwmcguire]

I would try it with the fuse pulled out of the fan and light switch off first

Still trips then a wire shorted

[16ACE27]

Pictures help a lot! Now that you (and we) know that its not a relay but a thermal overload protector, I would go with your 15 amp fuse test. If it burns - you have a problem downstream. If it works and powers the downstream items as normal then you probably have a bad thermal overload and need to find a replacement.

Her's some from Amazon with a push button reset:

https://www.amazon.com/Aramox-Overlo...omotive&sr=1-8

[Huck]

Originally Posted by 16ACE27

Pictures help a lot! Now that you (and we) know that its not a relay but a thermal overload protector, I would go with your 15 amp fuse test. If it burns - you have a problem downstream. If it works and powers the downstream items as normal then you probably have a bad thermal overload and need to find a replacement.



Her's some from Amazon with a push button reset:



https://www.amazon.com/Aramox-Overlo...omotive&sr=1-8

Thanks for the information! Unfortunately for me the 15 amp fuse blew as soon as the leads touched the ports they plug into. I pulled the fuse box out and looked in there as best as I could, but I’m going to have to pull in the bed slide to get access to all that electrical mess in there. It’s supposed to be cooler tomorrow, so maybe I can shut off power and investigate without electrocuting myself.
I sure hope this will be easy to find since it was working just fine until the power shut off and the coach switched to battery power. Nothing was moving or shaking and no one was even inside when this happened. I just came in to turn on the generator to keep the A/C on while the power was out, and heard the clicking.

[Huck]

Well I opened up the electrical compartment and this is what I found [emoji15]
Last night I tried a regular 15 amp fuse and it blew before I got it pushed in. This morning I put the thermal fuse back in and everything worked for a few seconds. Then it started clicking again after about 15 seconds. I pulled the thermal fuse back out and stuck it in the freezer. After that I opened up the electrical compartment and pulled all the trash out, I could by hand, that was left in there from the manufacturer. Then I put the thermal fuse back in and operated the kitchen fan for a little while. Then I pulled the fuse out of the fan and went to the bathroom fan, but about the same time as I was going to turn it on the clicking started again. This time I probably got thirty seconds out of it.
I think I’m going to try getting a new thermal fuse before I take it to someone who knows more about what they’re doing to find and fix the problem.

[16ACE27]

The fact that you blew the 15 amp fuse almost immediately tells you there is an overcurrent condition on that circuit. The thermal overload clicking is telling you the same thing. None of the loads on that circuit should pull 15 amps. So you can either wait until you get a new thermal overload (which you may need anyway depending on how long it was cycling) or brake out a multimeter or continuity tester and test the hot lead (the one that is on the downstream side of your thermal overload) to ground. Disconnect loads/wiring downstream until you no longer have a short to ground.

[Long & Winding road]

Thats what I would do.

Do you have a mulit meter?

I dont know a ton about electrical (But I'm learning). What I do is search on "You tube" for different things like "how to test for grounds", "...shorts", "...continunity" and watch a few of those. You might then deside its something you want to tackle your self (or not).

You can test the wires from the fuse panel to the fan (or whatever item thats affecting your problem) if you feel confortable.

Two years ago I was NOT confortable but since then I have added a ton of 12 v / 120 stuff and fixed so many factory problems (or potental problems) I dont mind digging around first.

Try unplugging (or unwire stuff - but tape them so they dont short out) and see what happens... could be a bad Fan or whatever is on your circuit.

[Huck]

I found the problem with the first thing I was trying to disconnect. With the shotty workmanship I’m surprised that it took over a year and a half for this issue to happen. Look at the bare wire sticking out beyond the crimped connectors. I’m still puzzled on why this happened when it did, and not sooner or when going down the road. Thanks everyone for your help and the education you gave me.

[16ACE27]

Glad you found it so quickly and it's an easy fix (that never should have needed fixing in the first place).

[Long & Winding road]

Job well done.

Im glad it was an easy fix.

[Huck]

I should have known it would be something like this, and I really should go through the wiring on the whole rig, because this isn’t the first issue I’ve had with crappy wiring connections. I have another post on here about my generator not providing any power, and it was because the wiring in the junction box right outside the generator was not connected properly. Don’t get me wrong I still love my coach, but the guy who did the electrical work must have been a meth head...