Pioneer DEH-P88RS-II Manuel D'installation page 7

Subwoofer output
(LOW/SUBWOOFER
OUTPUT)
The pin position of the ISO connector will differ
depends on the type of vehicle. Connect 6* and 7*
when Pin 5 is an antenna control type. In another type
of vehicle, never connect 6* and 7*.
Subwoofer
Perform this connection when using the optional amplifier.
Connecting cords with RCA pin
plugs (sold separately)
System remote control
+
≠
Power amp
(sold separately)
+
Subwoofer
≠
6