Optimus 120-2117 - Manual (Page 4)

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.
Follow the directions supplied with the adapter harness to temporarily
connect the power and speakers.
A selection of adapter harnesses is available at your local RadioShack
store.
Connecting Ground, Power, and Optional Components
Follow these steps to connect the supplied harness with the 14-pin
connector to ground, primary 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
screw attached to a metal part of the vehicle's frame. Be sure that
the screw is not insulated from the chassis by a plastic part.
3. Connect the red +12V TO IGNITION wire (with the in-line fuse holder)
to a point in your vehicle's fuse block that has power only when you
turn the vehicle's ignition key to either the accessory (ACC) or ON
position.
This connection turns on the stereo when you turn on the ignition or
turn the key to ACC, and turns off the stereo when you turn off the
ignition. This prevents your vehicle's battery from being drained if
you leave the stereo on when you turn off the ignition.
4. Connect the yellow +12V TO BATTERY wire (with in-line fuse holder) to
your vehicle battery's positive (+) terminal or to a point in your
vehicle's fuse block that provides a continuous source of 12 volts.
This connection provides continuous power for the stereo's LED
indicator when the faceplate is removed.
5. Cut the loop at the end of the blue AMP REMOTE TURN ON 500MA MAX wire,
strip about 1/2 inch of insulation from its end, then connect it to
any optional equipment (designed to run from a switched source) that
you want the stereo to turn on and off (such as a power antenna).