2021 Thor ACE 33.1 - No power on some low voltage lights

[ador]

We just arrived in Pensacola, FL. After setting up, my son pointed out that there is NO light on the dinette table overhead cabinet lights, USB ports dead, bathroom lights and vent fan dead, bedroom overhead lights and USB ports dead. 110 volt plug under cabinet in dinette area working, bathroom EGFI outlet working, bedroom lights working. All are on the SAME side of the RV.

I checked main breaker switch. Nothing tripped. Fuse panel under bed all OK. Anywhere else to check?

[Popfla]

Battery switch has to be in the ON or USE position for those 12 volt devices to work. Sounds like it's in the OFF or STORE position.

[javelin]

I don’t know your coach details, but my first quick read through your write up sounded like the 12vdc fuse (converter/end of the bed fuse panel) for the driver side house lights/loads is blown......but you say there are no blown fuses. The second read through you said bedroom light and usb ports don’t work; then later you said the bedroom light works? Maybe ceiling versus dresser? If the fuses are all good in the panel then possibly a bad connection/common ground wire broken somewhere in that specific feeder wire or a loose wire loom connector. Check the physical connection of the wires under screws (both ground and hot) on the fuse panel for the specific driver side fuse, for those failed loads. Maybe a wire was nicked during install that has now broken close to its mounting screw on the fuse panel and it broke off just from travel vibration. If nothing is obvious, I would contact Thor tech support and ask them for specific schematics for your DC wiring/connector locations and they also may be able to suggest where to specifically look for likely main connection points on the feeder for those DC loads that have failed. Good luck.

[ador]

I rechecked the fuse box just now. The #2 15amp fuse is blown. I replaced it and it sparked, blew the new 15amp fuse right away. Makes me think there are some wires that got tapped to each other when I was doing the slide outs? Any thoughts?

It is very possible that something may have come loose during our drive. Some of the roads are BAD. My pocket bathroom door became unhinged. My magnet board held by 4 screws fell off.


Should I turn OFF everything when changing blown fuse???
Did changing the fuse while everything is plugges IN caused the SPARK, which blew the new fuse?

[Jimbo56]

I’m not real good with electrical stuff, but I think the reason fuses blow is due to too much current draw. Sounds like you’ve got a short somewhere. Check for pinched wires around your slides. If you turn everything off and the fuse still blows when replacing it’s a short somewhere.

[javelin]

Well replacing a small blown fuse does not require turning off power normally; there is always the risk that the reason the fuse blew in the first place is still there (i.e., for a short circuit; if no actual repair was done) and as a result, it will blow again as you insert the new fuse. FYI: never replace a blown fuse with one rated for higher amperage.
Did any light bulbs get changed recently in any of the light fixtures that no longer seem to work? If yes, then it is possible that one of the fixture wires or the bulb socket is now shorting resulting in the blown fuse. If no affected lights or fans were recently manipulated then it is “possible” that the dinette (kitchen table) slide has caused wiring issues resulting in a short. Typically the bedroom slide base is stationary so wiring built into or running through the base normally should not flex as the bed slide is moved in/out. Are lights over the bed pillow area still working? If they are not and are on the same fuse as the rest of the failed loads, then checking under the bed for the short may be required. Otherwise I would suggest inspecting under the seats in the dinette slide closest to the bathroom first to see if you can find the DC wiring running through there and inspect it for snagging or obvious damage. There may also be AC wiring running to 120vac outlets in the seat area, but they should be separate from the DC wiring. It is also possible, if the DC wiring actually runs through that slide, that any items stowed under the seat may have also cut or damaged that wiring. Failing the inspections for an obvious wiring problem, calling Thor tech support may provide you with specific areas to check for wiring flex on those loads affected. Since you are under warranty the Dealer is an option if you can get into them of course.

[ador]

I am sure there are bunch of wires attached to what seem like a flat plastic (which serves as a holder for the wires), that extends when I extend the kitchen slide out. It then curves up when I retract the slide. I will inspect those when I retract the slide tomorrow before we leave FL.

The bedroom overhead light are out. But the MAIN bedroom lights have power. The bathroom light and vent fan are also out. This makes me think that they are all on the same power source as the dinette overhead lights and USB ports. If I can’t figure it out, I will schedule an appointment with the dealer when we get back to Vegas.

I just hope the power to the slide outs
Dont go out and the roof AC.

[javelin]

Your suspicion that all these various loads are powered from the blown 15 amp fuse circuit is very likely correct. Checking with Thor support for that fuse load record should confirm that (with some luck, since design is not necessarily “as built”). A short circuit on the hot wire from the 15 amp fuse could be anywhere......but I am “guessing” that it is most likely that the blown fuse hot wire has been pulled across some chassis (as in DC grounded) metal somewhere in its travel and the insulation on the wire has been skinned so that it is now grounded. The other option is a construction staple has now shorted both the hot and ground wires for that circuit.....somewhere.
It would be interesting to see if slide in or out makes any difference to the operation of the failed loads.......but it could cost you another blown fuse. If you had a multimeter and know how to use it you could test the load side of the hot fuse feed point (fuse out) to make sure no voltage is present first and if not, use the ohmmeter setting to measure hot to ground to confirm if a short is still there in both slide in/out positions. Never use an ohmmeter on a live circuit.
It might just be best to do as much visual inspection as you can to see if you can spot a chafed wire and repair it first........talk to Thor support for assistance or get to a Dealer (but the Dealer wait could be very long). The other option would be a mobile RV tech but they would probably do the same inspection first that you are already doing.

Finding a staple short circuit could be much more difficult search since many are buried during construction.

The slides are usually powered from a 30 amp DC fuse in the bed end converter/fuse panel and the roof A/C is 120VAC powered not DC (other than the thermostat A/C call for cooling circuit is DC powered). Good luck with your search.

[16ACE27]

Originally Posted by ador

The bedroom overhead light are out. But the MAIN bedroom lights have power.

In my world the bedroom overhead lights are the MAIN bedroom lights. All other bedroom lights are in the vanity or under the cabinets over the head of the bed.

[ador]

I will look for wirings under the dinette seat and the bunch of wires on the left of the dining slide out and look out for any obvious stripped or bunched up wires that may be causing the 15amp fuse to trip. Im not good at electrical stuff. In fact, Im really nervous when it comes to electrical as I dont want to cause any fire. I just want to finish this 21day road trip of ours without any other issues.

[Wiley1]

As a troubleshooting aid, turn off every 12v switch that you can find. If the fuse still blows when you change it, the short is on the supply side of those those switches, not on the load side of any one. That helps only because it reduces the possible points of failure by about a third.

Your next problem is to figure out how all those circuits are tied together. You might have 3 or 4 wires coming out of your fusebox of the same color or there could be just one wire that is spliced somewhere into 2 or 3 routes, or all those devices could be daisy-chained, one after the other. You can bet that Thor elected to use whatever method required the least copper.

A wiring diagram would be a huge help. You should be able to download one here:
https://www.thormotorcoach.com/owner-resource/

I like your theory about the slides catching on something, if the lights were working before you made camp. Have you tried retracting the slides to see if the short goes away? You're likely to burn a fistful of those little blue fuses before you pinpoint this issue.

[ador]

Just want to provide an update on this issue. We are done with our trip and have returned home last week. Yesterday, I had some time to do some more work on minor fixes on some problems we had during the trip.

So, I turned off my main circuit breaker and replaced the 15 amp fuse (for the second time). The first time I replaced it in the campground, the new fuse blew right away. My guess is, with me sliding out the main slide when I was doing some cleaning, cleared whatever wires that were touching and causing the fuse to blow up during the trip. The lights went back on in the dinette, restroom and bedroom overhead lights (not the main ceiling lights). I will continue to look around for some loose wirings or connections.

[Wiley1]

You have to ask yourself this question: What has changed between when the fuse blew and when the fuse didn't blow. Probably a whole bunch of things but the main ones are: the slide is now in and a whole lot of shaking and vibration during the trip home.

I would bet that your slide is pinching the 12v wire that feeds the switch for overhead light in the bedroom. Just because this issue has gone dormant doesn't mean it is fixed. It is likely to come back the next time you fully extend the slide. Best to find it while you're in your home port so it doesn't ruin your next trip.

[ador]

I agree Wiley. I have downloaded the electrical diagram from Thor owner website. It looks Greek to me. But I will try to analyze and see If I can locate some wirings that is accessible. There is a bunch of wires that are bundled up and zip tied to a black, flat plastic (that they use to hold them in place, bends inward when retracted and straightens up when slide is extended). It is visible, but not accessible without removing the living room slide out.

I have an appointment with the dealer Sept. 14th for some warranty items that need to be fixed. I will surely include this incident (issue). Since it is currently working, I hope they will still look into this matter.

Originally Posted by Wiley1

I would bet that your slide is pinching the 12v wire that feeds the switch for overhead light in the bedroom. Just because this issue has gone dormant doesn't mean it is fixed. It is likely to come back the next time you fully extend the slide. Best to find it while you're in your home port so it doesn't ruin your next trip.

[Wiley1]

This is just one reason why my little 24 ft Class-C has no slides.
Another? Leaks.

[ador]

No leaks whatsoever. I sealed all the windows with Flexseal after delivery. I also applied 6 inch Eternabond tape to all roof seams. We drove through some HEAVEY Rains in Missouri, Florida and Texas during this past trip. No water leaks anywhere (Thank God).

The living room slide (lower front part) started developing gap, about 1/4 to 1/2 inch. And I noticed the some part of the lower rail have some "gouges". Might need re-adjustment. Cigarette lighter outlet stopped working (I use this for my GPS and TPMS). The Propane Electronic gauge was NOT working since delivery. Was promised that they will order a replacement panel. As it turned out, I have to bring the RV in for inspection so the dealer can request approval for warranty work. And lastly, the electric outlet on the dinette seat was NOT working since day 1.

Originally Posted by Wiley1

This is just one reason why my little 24 ft Class-C has no slides.
Another? Leaks.