You can use a battery (like AA) and a bit of wire to determine which wires are positive/negative. take a guess at a negative terminal and hold it to the neg. side of the battery. Then touch the other speaker terminal or wire to the pos. side of the battery. If the speaker moves in, you've found positive. If it pops out, then you're backwards and you're touching pos. to neg..

That's a handy trick for when you're behind the dash wondering which wires go to which speaker. Trick is you need to see the speaker which is usually hidden behind a grille. If you already have the speaker out, check on and around the speaker terminals for a "+/-" marking.

I'm no help when it comes to the impedence. For reasons I do not remember I had always thought that the stock speakers were six Ohm.

--Will
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850 / Mini