We’ve been getting the itch to go camping, and the mandated social isolation seems like a perfect opportunity to change our scenery. We made reservations for next week, and will be getting a full-hookup site at a campground a little under one hour from home. The full hookup site will be nice to un-winterize the water system. Today I uncovered the camper, installed the propane tanks and hooked up the battery.
When I went to hook up the battery, I made a mistake that could have caused a lot more damage than it did. I am thankful for strategically-placed fuses that protected the electrical system and appliances, and prevented this from becoming a much more expensive mistake than it was.
The Cause
First of all, I will detail the mistake I made, maybe I can help someone to not repeat it.
As far as I can find, our 2016 Sunset Trail 330BH is not unlike most other travel trailers in that the wiring is installed more like house wiring than automotive wiring. The wire colors are black and white, not red and black.
For reference, white is neutral (-) in house wiring and black is hot (+). In automotive wiring, black is neutral (-) and red is hot (+). So the battery connection should be white cable to black terminal, and black cable to red terminal.
In a mindless moment, I connected the black cable to the negative terminal (matching black to black) and the white cable to positive. This is what is known as “reversed polarity” and most systems in the trailer don’t like it very much!
The Effect
Apart from the large spark that occurred as I connected the white cable to the positive terminal of the battery, I blew many fuses throughout the trailer. I started to figure this out when I went to turn the heat on. Here’s what I found.
In the load center, I found that all four of the 20-amp “Reverse Polarity” fuses (the four yellow fuses in the center of the above photo) were blown. I replaced those and the inverter fired up (I was attached to 15-amp shore line by this time). Still no furnace though.
As I was checking the thermostat, I noticed that the stereo display was also not on and the stereo unit would not turn on. I found a 10-amp fuse tucked in near the wiring harness connector in the back of the stereo head unit. It was somewhat camouflaged (looked like the release tab for the connector at a quick glance), but it was there. Quick swap out had the stereo working again.
I finally found the culprit that was keeping the furnace from working, it was a glass fuse in the thermostat housing (on the very right of the thermostat circuit board in the above photo). I don’t have the fuse to swap with it at the moment, but I was able to test the furnace by jumping the two holder clamps for long enough that the thermostat display came on and the furnace blower kicked on.
Update: I found the glass fuse that I needed in an assortment pack of glass fuses at an auto parts supply store. I could have ordered only what I needed online, but it would have taken a week to get here, and by the time I paid for shipping, it would not have been any cheaper than just getting the assortment pack.
The only difference between the fuse that was in the thermostat and the one that I found to replace it is the old one was a “slow blow” fuse and no one seems to stock those locally (I miss Radio Shack). The “fast blow” one seems to work, at least for now. I’ll order add a slow-blow version to the next parts order I put in online.