Exterior lighting issue 3120RL

[OShag]

Greetings. I'm looking for (hopefully) someone who has found the solution to a 12v issue I'm having. The 15a (12v) fuse keeps blowing that services our "Exterior" light (the yellow one outside above the door) and the exterior lights under the stairs, near the hitch and under the skirt near the sewer hookup. The door light is operated through the InCommand panel, and the rest are all switched via the toggle switch in the panel (one switch for our front cap LED accent lights, one for the exterior lights in question, and one switch for the pendant lights over the kitchen island).

When I first found the lights didn't work, I replaced a blown 15a fuse in the 12v panel. They worked - until I turned them off and tried to turn them on again. So, I started looking further. I pulled the fuse panel cover and ensured all the post screws were tight. I did find the factory crimped on fork (that the screw tightens down on) was crushed. So I fixed that. I also checked the wires into the back of the rocker switch - o.k. there too. The lights worked again, until turned off and back on. Then, I checked the fuse holder (the prongs the fuse slides in to) and they were loose. I tightened them. The lights worked again. This time, through several cycles of off and on. But they stopped again after a day - and no movement of the 5er.

I don't know where to start next. If it was all in the wires (i.e. all controlled by the rocker switch), I would start tracing wires, but what's holding me up is one of the lights (Exterior - over the door) is switched by the InCommand panel, while the rest are controlled by the manual switch.

Has anyone had a similar issue and found the cause? I am comfortable with the electrical work, but I want to figure out where to start looking. Thank you in advance.

[rohrmann]

Besides the possibility that a wired is shorted, you might want to check the fixtures for water in them. Years ago, I found the large round scare light on the door side was half full of water, which caused the light to not work, and the corrosion was getting to the point where it would have started blowing a fuse.

[OShag]

Thank you. No water in the fixtures (I forgot to post that). Which is a bit amazing considering the rain we had coming home from our last trip. That was one of the first checks after the first fix didn't hold.

[1wayhighway]

Have you inspected the relay panel in the pass through area? That is the panel the in command sends commands for operating the different systems. Maybe a bad power connection there, would just be a matter of identifying which one controls that light.

[OShag]

I'm hoping to get by storage tomorrow and will look closer at the basement panel. I looked at it briefly while driving cross-country, but will take some more time as soon as the PNW rain lets up to see if there are any loose connections or power issues there. Thanks, I'll post what I find after getting over there.

[rohrmann]

A loose wire is less likely to cause a fuse to blow, but a short is the likely reason, and can be in a fixture or maybe where wire passes through the frame or got chafed on any metal where it is located.

[firestation12]

If the fuse blows with all the switches in the off position, it’s unlikely the light fixtures are the issue since there is no switched current being sent to the fixtures.

[OShag]

Sorry for anyone who's been watching, life got in the way...

I ended up pulling all 5 lights and the over the door light when I finally got the RV out of storage. The factory used closed-end crimp connectors (photo attached - NOT from my RV) and demonstrated "not-so-careful" attention to detail. The wires were all stripped back so far the exposed copper was sticking out of the ends of the connector. I ended up cutting all the crimp caps off and wired everything back together ensuring good contact. Put all the lights back on and everything has been working since then. Took a trip to AZ and the lights worked the whole time and no more blown fuse. I'll chalk it up to rushed/poor/careless/?? work at the factory but it all seems to be resolved now.

One interesting note, when I pulled the panel in the basement, I saw one sticker near where the wire went into the back of the InCommand panel with a "4" on it. There was another "4" sticker inside the 12v fuse panel inside - after pulling off the cover to check wire connections. I had asked Keystone for a wiring diagram and received a "Sorry, we can't help" reply but they did include a "standard wiring diagram" that listed the labels for each circuit - no picture or layout where the wires should be or in what order they connected stuff. Of course, the problematic lights are on wiring run #4. Looks like someone already tried chasing down the problem before we purchased. I guess they never pulled the lights and checked their individual connections but assumed the problem didn't really exist after checking continuity on the wiring.

Oh well, fixed for now. Thanks to all the feedback.