97 astro speaker wire .?

hello to all

i have a 97 astro van with a 8 speaker system 2 front +2 front tweeter, 2 on rear pillars and 2 factory sub on rear halve doors.i need speaker the wiring diagram to determine + and - on the wires to change speakers

thanks 

Using a battery, AA, AAA, C, D, or a 9volt.  and a short length of speaker wire.  Connect the speaker wire to the 2 terminals of the OEM speaker.  Now touch the other end of the speaker wire to the battery.  One wire on negative terminal of battery.  Other wire to the positive terminal of the battery.  This will make the cone of the speaker move.  If the cone moves away from the magnet, you have the positive terminal of the battery connected to the positive wire of the speaker.  Label that terminal as positive and plug the factory plug back into the speaker, notice which of the wires is connected to the positive terminal of the speaker.  That is your positive wire.

The above will not work on the tweeters.  Once you identify the wiring on the woofers or mid bass drivers, place the tweeter on side of that driver, magnet facing you with terminals closest to you.  The positive terminal of the tweeter will be in the same location as the positive terminal of the other speaker.