Black connector:

1 DK GRN 1947 Audio Return - Left Front - Low Level
2 TAN 511 Audio Signal - Left Front - Low Level
3 LT GRN/WHT 1948 Audio Return - Right Front - Low Level
4 LT GRN 512 Audio Signal - Right Front - Low Level
5 BLK/WHT 351 Ground
6 GRY/BLK 308 Parklamp Switch Signal - ON
7 BRN/WHT 230 Instrument Panel Lamps Dimmer Module Output
8 — — Not Used
9 YEL 43 Fused Output - Accessory
10 ORN 640 Fused Output - Battery

White connector:

11 BLK/WHT 351 Ground
12-13 — — Not Used
14 DK BLU 1796 Steering Wheel Controls Input
15 DK GRN 835 Entertainment And Comfort (E&C) Serial Data Communication
16 — — Not Used
17 LT BLU 115 Speaker Feed - Right Rear
17 BLK 1946 Audio Return - Right Rear - Low Level (U85)
18 DK BLU 46 Speaker Feed - Right Rear
18 DK BLU 546 Audio Signal - Right Rear - Low Level (U85)
19 YEL 116 Speaker Return - Left Rear
19 BRN/WHT 1999 Audio Return - Left Rear - Low Level (U85)
20 BRN 199 Speaker Feed - Left Rear
20 BRN 599 Audio Signal - Left Rear - Low Level (U85)

The first connector I listed appears to be for a CD changer.

I'm pretty sure that these pinouts are at the radio end of any connector, which was driving me bat **** trying to trace the wires in your pictures.

This is for a 99 GP.