Optimus 120-2154 User Manual page 8

Connecting Two Pairs of Speakers
If you are using both front and rear speakers, follow these steps to
connect the harness with the 14-pin connector to the speakers.
12-2154 Only: Before connecting the speakers, remove the tape that holds
the mounting sleeve in place and slide the sleeve off of
the stereo.
to 4CH.
(Violet/Black) - Rear Right Speaker (-)
1. Connect the gray wire to the right front speaker's positive terminal.
This terminal is usually marked with a plus (+) sign or red mark.
2. 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.
3. Connect the white wire to the left front speaker's positive terminal.
4. Connect the white/black wire to the left front speaker's negative
terminal.
5. Connect the violet wire to the right rear speaker's positive terminal.
6. Connect the violet/black wire to the right rear speaker's negative
terminal.
7. Connect the green wire to the left rear speaker's positive terminal.
8. Connect the green/black wire to the left speaker's negative terminal.
Connecting One Pair of Speakers
For 12-2155: If you are using only one pair of speakers, follow Steps 1-4
in "Connecting Two Pairs of Speakers" above to connect the
harness with the 14-pin connector to the speakers.
Then set 2CH/4CH on the bottom of the stereo
(White) - Front Left Speaker (+)
(White/Black) - Front Left Speaker (-)
(Gray) - Front Right Speaker (+)
(Gray/Black) - Front Right Speaker (-)
(Green) - Rear Left Speaker (+)
(Green/Black) - Rear Left Speaker (-)
(Violet) - Rear Right Speaker (+)