Tandy 120-2157 - Manual (Page 7)

optional equipment, designed to run from a switched source, that you
want the stereo to turn on and off (such as a booster or a power
antenna). Cut the loop at the end and strip about 1/2 inch of
insulation for connection.
Note: This wire does not provide power to the components. It simply
turns them on or off. If you do not use this wire, secure it with
a wire tie and do not let it touch metal.
Connecting an Equalizer/Booster
If you are connecting the stereo to a separate equalizer or booster, you
need additional wires (not included).
To increase the total power output from your system, connect the R (right)
and L (left) line output jacks on the back of the stereo and blue/white
wire, if necessary, to the equalizer or booster.
Refer to the equalizer/booster's owner's manual for directions.
Connecting 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. If you are
using only one pair of speakers, follow Steps 1 - 4 only.
1. Connect the gray wire to the right front speaker's positive terminal.
This terminal is usually marked with a plus (+) sigh 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 (-) sigh, 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 rear speaker's negative