I have the 1998 V70 wiring diagram. Perhaps the colors are identical to 1997.

Front dash:
Left + red-white
Left - yellow-white
Right + yellow-green
Right- green
Front doors:
Left + green-white
Left - green-brown
Right + red-black
Right- red-white
Rear doors:
Left + brown-white
Left - brown-black
Right + pink-black
Right- pink-white

Cargo area speakers are connected in parallel with the rear door speakers.
Power connections:
fused battery direct green-brown (2 wires)
switched batttery (acc) yellow-violet
power antenna motor blue-white
ground (chassis) black (2 wires)
illumination pink
speed sensor yellow-black

It sounds like your adapter has illumination bridged to battery direct, which is wrong. This would cause of the instrument panel lights to turn on at full brightness.