Optimus 120-1998 - Manual (Page 4)

If you install speakers, avoid routing the speaker wire near moving parts
or sharp edges. You can usually route it along the wiring channel
beneath the vehicle's door facings by carefully removing the molding that
holds the carpet in place. After you route the speaker wire, replace the
molding.
Testing the Stereo
Before you mount the stereo or any speakers you are installing, test the
stereo by temporarily connecting the speakers, power wires, and antenna.
Important: Do not cut these wires. If you cut any wire, you cannot
obtain a refund or exchange on this product. Radio Shack
will provide warranty service if you cut a wire and find the
product is defective.
MAKING THE CONNECTIONS
The supplied 14-wire harness includes all the lead wires you need to
connect the stereo to speakers, power, and optional components. You might
need additional wire, depending on your individual auto sound system, to
complete connections. Your local Radio Shack store carries a full line of
wire and wire management accessories.
Cautions:
* For added safety and to protect your stereo, disconnect the cable from
your vehicle battery's negative (-) terminal before you begin.
* Be sure your speakers can handle 9 watts of power (4.5 watts per
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 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.
Using an Adapter Harness
If you are replacing an existing stereo, or if your vehicle has been
factory-wired for autosound components, you might be able to use an
adapter harness to connect the power and speakers. Radio Shack stores
sell adapter harnesses for most vehicles.
Follow the directions that come with the adapter harness to temporarily