Optimus 120-2152 - Manual (Page 6)

Cautions:
For added safety and to protect your stereo, disconnect the cable from
your vehicle battery's negative (-) terminal before you begin.
(new illus)
Be sure your speakers can handle 32 watts of power
(16 watts power channel). Each speaker must have an impedance
of at least 4 ohms. Your local Radio Shack store carries a full
line of speakers.
You must connect the GROUND, +12V TO IGNITION, and +12V TO BATTERY
wires first, then make all other connections as described in the
following sections before you plug the harness with the 14-pin
connector into the stereo. If you do not make connections in the
order shown, damage to the stereo is possible if any wire connections
are made incorrectly.
You must connect a separate wire to each speaker terminal as described
in the following procedure. Do not use a common wire or chassis
ground for any speaker connection.
Note:
The wiring harness has the following labels.
Using an Adapter Harness
If you are replacing an existing stereo, or if your vehicle has been
factory-wired for auto-sound components, you might be able to use an
adapter harness to connect the power and speakers. Radio Shack stores
sell adapter harnessers for most vehicles.
Follow the directions that come with the adapter harness to temporarily
connect the power and speakers.
Connecting Ground, Power, and Optional Components
Follow these steps to connect the harness with the 14-pin connector to
ground, primary and memory backup power, and optional components.
1. Disconnect the cable from your vehicle battery's negative (-)
terminal.
2. Connect the black ground wire to a chassis ground, such as a metal