Optimus 120-2113 - Manual (Page 7)

Connecting Two Pairs of Speakers
If you are using both front and rear speakers, follow these steps to
connect the harness to the speakers.
(connector)
___________
Left |___________| Right
|||| ||||
(+) White__________|||| ||||___Gray (+)
Front ||| ||| Front
(-) White/Black_____||| |||____Gray/Black (-)
|| ||
(+) Green____________|| ||_____Violet (+)
Rear | | Rear
(-) Green/Black_______| |______Violet/Black (-)
1. Use a small screwdriver to move 2 ch/4 ch on the bottom of the stereo
to 4 ch (four channel).
2. Connect the gray wire to the right front speaker's positive terminal.
This terminal is usually marked with a plus sign or red mark.
3. Connect the gray/black wire to the right front speaker's negative
terminal. This terminal might be marked with a minus (-) sign or it
might not be marked at all.
4. Connect the white wire to the left front speaker's positive terminal.
5. Connect the white/black wire to the left front speaker's negative
terminal.
6. Connect the violet wire to the right rear speaker's positive terminal.
7. Connect the violet/black wire to the right rear speaker's negative
terminal.
8. Connect the green wire to the left rear speaker's positive terminal.
9. Connect the green/black wire to the left rear speaker's negative
terminal.
Connecting One Pair of Speakers