Hey everyone. I purchased an auto-dimming mirror w/compass and temp from Ebay a couple of months ago. I installed the mirror sucessfully..took me about 3 hours. 2 weeks later, the mirror went out. The 5 amp fuse that came with the mirror had blown. I replaced the fuse and 15 mins after installing the fuse, the fuse blew out again.
I'm tapping the 12v wire and the ignition wire into the radio wires. I have no clue as to why it keeps blowing out. I would have tapped power from the map lights, but where would I have gotten the ignition wire from? So I did everything down below, into the radio. Any sugesstions?
Oh yea, newb here :)
If it's blowing fuses it's most likely not the power source you tapped, but the device itself. Fuses are used to protect the wiring inbetween your power source and your device. If the fuse is blowing it is because more current is being consumed then the fuse will allow.
I would contact the manufacturer first and find out how much current the mirror is supposed to draw. You can then use an amp meter in series with the fuse and find out how much current your mirror is drawing. If it draws more then it's spec'd to draw then the mirror is at fault.
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Kevin Pierson
Thanks for the reply. Being that it came with a 5-amp fuse, would I be able to drop in a 10-amp fuse just to see if it'll happen again? I'm trying to find the specs on this mirror, but I cant find anything as of yet. The mirror is made my Exon Science, a Taiwanese-based company that deals with rear view mirrors and auto glass. I'll shoot them an email...hopefully they'll reply. When I get some time i'll follow your advice and see how many amps are really going thru that wire.
Many thanks again
The short answer is no, as it is possible that the internal circuity is not capable of dissipating >5A of heat and would become a fire hazard.
Again, fuses are to protect the wiring (and associated circuitry) from having to dissipate more heat they they can physically dissipate.
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Kevin Pierson
Thanks for the replies...I got an email back from the Ebay seller that I got the mirror from...he says that the documentation provided with the mirror was 100% wrong. I cannot connect the 5-amp fused wire to a battery wire on the radio. Instead, the best way to do it is toh have the wire run straight to the battery(+) but can't connect it to an existing wire that may be shared with other things in the car.
Now I see that no matter what, I must have that wire go straight to the battery...this wire is too short for that. Can I:
- Solder the existing wire to a separate wire (from Home Depot maybe) that's long enough to reach the battery
- Tap power from a fusebox or something that has a wire going straight to the battery something similar
I wanted to wait until the weather got warmer but I have a friend of mine that will lend me his garage for a few hours on Saturday to do it. What would be the best thing to do?
1998 Mazda MPV LX 4WD
Which fuse are you blowing?
If you are blowing an inline fuse to the mirror it doesn't matter where you tap in to the electrical system at it will still blow the fuse.
If it's blowing the fuse for the radio (where you tapped power) then going to the battery may help.
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Kevin Pierson
The mirror's fuse it's what's blowing. The radio would still be playing and the mirror would just go dead. So I guess that I have a defective mirror? 
I would say that that is a very good possibility. No matter where you connect it to the cars electrical system it will still draw the same amount of current, which is what is blowing the fuse.
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Kevin Pierson
Hey, thanks alot buddy. You've cleared up alot of confusion for me. Sorry for being a newb wanting to do a DIY job. I wont even bother trying to do anything to it.
I'll talk to the guys that sold me the mirror and ask for a replacement mirror since it's under warranty for up to a year.
I'll post an update later