Not sure why it would be different, however, any wire with a stripe is the negative.
WRONG... Never trust a car wire color to be ISO.
if youre doing lets say a toyota, one the speakers will have a Yellow and a black wire.. the black is (+) and the yellow (-)
To the OP:
I havent done the speakers on the cube yet but here's a easy trick to find the polarity if your wire.
- You will need a AA (AAA and 9V also do)
- With your Unplug OEM speaker use the battery to find out which terminal is + or -
simply tap the + of the battery to one of the terminal and the - on the other one.
If the speaker pop out it mean you successfully found the +
Then you check with the factory harness which wire is coming out of the - so here you got your color wire.