Anybody know which wire is + or - on a 99 firebird?

[firebird19_99]

Anybody know which wire is positve and which is negative on a 99 firebirds speaker harness non-monsoon?
Anybody know which wire is positve and which is negative on a 99 firebirds speaker harness non-monsoon? colors are not red and black but rather like a greenish aqua color so i have no way of knowing. Is their anyway to test to see which one is which?
Anybody know which wire is positve and which is negative on a 99 firebirds speaker harness non-monsoon? colors are not red and black but rather like a greenish aqua color so i have no way of knowing. Is their anyway to test to see which one is which? Also which gauge wire should i use? thanks

 

[Oreif]

Here are all the wire colors for the non-monsoon stereo set-up:

A Left Front Spkr (-) Light Gray
B Left Front Spkr (+) Tan
C Right Front Spkr (-) Light Green
D Right Front Spkr (+) Dark Green
E Ground Wire Black
F Not Used
G Headlight Dimmer Wire Gray
H Power Antenna Turn On Pink
I +12 Volt Ignition Wire Yellow
J +12 Volt Battery Wire Orange
K Right Rear Spkr (-) Light Blue
L Right Rear Spkr (+) Dark Blue
M Left Rear Spkr (-) Yellow
N Left Rear Spkr (+) Brown

Speaker wire stock is 18 gauge.