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Old 05-26-2015, 01:07 PM   #1
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lights/fan not working on 12V

I recently inherited a 2005 Forest River Flagstaff popup trailer. It did not have any manual and I haven't had a 'walk through' from a dealer..yet. I went around the trailer and with the help of a neighbor who is an RV enthusiast was able to figure pretty much everything out.

However, I am having issues with the interior lights and ventilation fan not working off the battery power. When the trailer is plugged in to shore power the interior 12v stuff works, lights/fan run fine (from reading the forums this suggests the switch under the range is working fine, or the lights wouldn't work under shore power either). However when the trailer is not plugged in to shore power (and battery is verified 100% charged) the interior lights and ventilation fan will not operate.

I checked the fuses in the breaker box and flipped the breaker switches on and off. I know the lights and fan work because they run when shore power is connected. Any suggestions as to why they won't run when no shore power is connected and the battery is in working order? Btw, the battery works the electric motor that raises and lowers the camper just fine.

Any direction is greatly appreciated!


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Old 05-26-2015, 01:26 PM   #2
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Be looking for a Resetable circuit breaker under the A-frame tongue.
Follow the positive battery cable to it possibly.

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Old 05-26-2015, 01:53 PM   #3
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I had the trailer plugged in to shore power to keep the battery charged and to let the fan run to air out the trailer after being packed up all winter. I went out to look for a circuit breaker on the outside as you suggested, and just to be safe unplugged the shore power first. I checked the battery and looked for a circuit breaker but all I found was the in-line fuses on the pos+ battery connections. I then noticed that the fan was working, and hadn't shut off when I unhooked the shore power. I tried the lights and they work fine. I don't know what I did but it's now working.

While my symptoms are resolved I'm curious to know what might cause this scenario? If it continues to occur I'll post more..

Thanks for your help!
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Old 05-26-2015, 02:37 PM   #4
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It seems to me that maybe the battery was not charged. How did you verify the battery was charged (not trying to insult your intelligence)? Or it could be a weak ground?
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Old 05-26-2015, 05:38 PM   #5
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It may be a corroded connection on one of the wires. By moving wires around a bit when you were checking the in-line fuse you may have made connection again.
Check all your wiring for corrosion in and around the battery box.

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fan, light

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