I pulled my TT from storage the other day and hooked up a freshly charged battery. First the positive terminal then negative. I noticed quite a spark when I connected the negative terminal, but thought that should not be a that unusual. But I double checked the polarity as OK just to be sure.I entered the TT and found that all my 12V endpoints do not work. Went to the fuse panel and found both main 40 amp fuses blown. Anyone have any ideas what would cause both main fuses to blow. I will go ahead and replace them today, but am concerned I might have an underlying problem. Though I am not sure what that would be.

If both polarity fuses blew you need to recheck the polarity. Don't go. Y the color of the wire, find the one that goes to ground and hook that one to the "-" post.

Sounds like a short circuit that was open until you made the second connection. If the rig was grounded connecting the positive side of the battery would have blown the C/B also.Of course, where the short is...? Anything different from when you put the rig away? Any new work? If it was me I'd hustle the RV to my dealer who has smarter people working there than I.

Those are not polarity fuses, but they mite have blown if polarity was backards.Otherwise look for a dead short circuit. Remove all other DC fuses, then check again. Use process of eliminization ! :)

Do you have a wire that was on the battery that is now disconnected and laying on the frame? If that circuit was powered that may have caused a short circuit. To blow the 40 amp main fuses, you would need to have a dead short or reversed the polarity.

A piece to the puzzle. I put a meter on the battery. This polarity is reversed.This can happen????? I did not think a battery could reverse polarity. How does that occur?Maybe a short in the battery. Is it possible that I charged the battery with reverse polarity? How would I fix that?

Blown fuse help | Good Sam Community

14 Replies

westend
Explorer
May 15, 2015
Do you have a wire that was on the battery that is now disconnected and laying on the frame? If that circuit was powered that may have caused a short circuit. To blow the 40 amp main fuses, you would need to have a dead short or reversed the polarity.
RJsfishin
Explorer
May 15, 2015
Those are not polarity fuses, but they mite have blown if polarity was backards.
Otherwise look for a dead short circuit. Remove all other DC fuses, then check again. Use process of eliminization ! :)
Dick_B
Explorer
May 15, 2015
Sounds like a short circuit that was open until you made the second connection. If the rig was grounded connecting the positive side of the battery would have blown the C/B also.
Of course, where the short is...? Anything different from when you put the rig away? Any new work? If it was me I'd hustle the RV to my dealer who has smarter people working there than I.
K_Charles
Explorer
May 15, 2015
If both polarity fuses blew you need to recheck the polarity. Don't go. Y the color of the wire, find the one that goes to ground and hook that one to the "-" post.

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Blown fuse help

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