Crap...I think dark blue and brown are +...or maybe the wires aren't even that color...it's been too long.
There was a rule I used to remember and I thought it was the darker wire was positive. But don't quote me on that one. Use a small battery and touch it to the speakers. If the speaker pushes forward then you have the right polarity. If it pushes backwards you have reverse polarity.
One easy place for remote is the back of any cigarette lighter.