I screwed up!

[Finder9]

So I was upgrading my bathroom fan and think I reversed the polarity when reinstalling. Now no lights in bathroom. How bad is it?
Are the bulbs blown? Haven't wired up the fan yet. Disgusted over stupid move.

[Finder9]

Uh huh -- the light switches have to be in the on position for the red light next to the fuse to light and show a bad fuse. If you don't turn on the switch the red light will not light. Never knew that.

[Blazing_Zippers]

I ask this because, well--I know. IS THERE A SWITCH ANYWHERE?

[Finder9]

Update:
Chris, you were correct. With the switches on (a load) a red light was on next to the fuse. Replaced same and lights work fine. Figured out what was positive and negative and wired fan. All good.
Thanks again.
Jack

[rkentzel]

make sure you did not drop a ground

[Bobbo]

Don't trust the red lights. For them to work, the circuit has to be pulling current. If you turned the light back off, then looked at the red lights, they won't light up.

Pull each fuse out of the board and test it.

[Finder9]

Thanks all. I should know all this but when it comes to electrical matters I lose any self confidence I may have had and it's panic time. I'll look at it again today when I get up to the fifth wheel. Can't keep it at home because of my driveway from hell. Thanks again. Nice to know help is close/

[Old-Biscuit]

BLACK wire should be positive .... WHITE wire should be negative

Bulbs blown (should show dark spots)
Fuse blown...test them don't just look

Reverse wires and see if lights work (UNLESS LEDs....they will blow if reversed polarity)

Connect fan and see of it works..won't hurt it which way wired, will just run in reverse if wiring is backwards

[kyle86]

On most 12v fuses, the two main metal pieces have a small opening in the plastic over that you can insert the prongs of a multimeter. $3 or free harbor freight multimeter on the ohms or volts setting is fastest way to check fuses. On ohms, just make sure the main dc breaker is off or battery disconnected. With the meter on volts and main dc breaker on/batt hooked up, you just hold one side on ground that all the black wires are connected to, on the red just probe the fuses on each side of the fuse. Test lights makes this extremely fast. On ohms setting a prong is held on each side of the fuse. You are measuring resistance(impedance) 1 indicates blown fuse and 0 indicated good. On vols setting you want 12v+ on the meter or a beep from test light on both holes in fuse.

Correction: Your meter may vary. You may need to remove yhe fuse for testing on ohms. I am not an expert.

Moderator edit to re-size picture to forum recommended limit of 640px maximum width.

[JiminDenver]

Every trip I think the bathroom lights are out until I remember that they are on a wall switch too.

[csamayfield55x]

Dennis M M wrote:
Never saw a fuse box with a red light, doesn't mean there aren't any. Sometimes you can see one fuse has a broken filament. Best way to check is with a test light.

A short should not have any effect on the bulbs, just pop the fuse in the circuit. That's what fuses are for and there should not be any other damage.

Many of the new fuse panels (like mine) show a red LED next to a blown fuse. You don't want to count on these because they only work if the load is being called for. If you shut the switch off the red light might not come on. Use a test light or a volt meter to know for sure

Chris

[rekoj71]

Some LED bulbs won't work with polarity reversed, but a regular incandescent should still light.

[Dennis_M_M]

Never saw a fuse box with a red light, doesn't mean there aren't any. Sometimes you can see one fuse has a broken filament. Best way to check is with a test light.

A short should not have any effect on the bulbs, just pop the fuse in the circuit. That's what fuses are for and there should not be any other damage.

[SDcampowneroper]

Reversed polarity on a 12 v dc system should only cause the fan to run reverse of the switch indication in an isolated condition. I suspect that grounding by reverse polarity popped your fuse. Shouldn't be any other harm.
Test your wiring for correct polarity.

[Dutch_12078]

All reversing the polarity would do is make the DC fan motor run backwards. Unless you shorted the wires and blew a fuse, it's more likely that you might have a bad connection that's interrupting either the ground or hot wire to the lights. Were there more than two wires at the fan power connections?