Try this;
Connector A - 8 Pin DIN ISO
Pin Color Description
A01 Blue ESP/ETS/BAS control module, speed dependant volume control, VSS NAV
A02 Green Data link connector (DTC readout) / Phone mute
A03 Gray Backup lamps reverse NAV
A04 Red Battery (circuit 30) +12V constant on, fuse F21 25A
A05 Orange FM AM WEATHERBAND amplifier Standard radio
A05 Orange FM AM WEATHERBAND amplifier and Bose premium sound system power trigger
A06 White PWM dimming and DAY/NIGHT headlight, instrument lights
A07 Pink Power (circuit 15) +12V switched, ignition, fuse F10 10A
A08 Brown Ground
Connector B - 8 Pin DIN ISO
B01 Red Right rear door speaker + Bose premium sound system (150 Watts 6 channel, 2 circuit bass woofer)
B01 Red Right rear door speaker + Standard radio
B02 Gray Right rear door speaker - Bose premium sound system
B02 Gray Right rear door speaker - Standard radio
B03 Orange Right front door speaker + Bose premium sound system
B03 Orange Right front door speaker + Standard radio
B04 White Right front door speaker - Bose premium sound system
B04 White Right front door speaker - Standard radio
B05 Blue Left front door speaker + Bose premium sound system
B05 Blue Left front door speaker + Standard radio
B06 Green Left front door speaker - Bose premium sound system
B06 Green Left front door speaker - Standard radio
B07 Pink Left rear door speaker + Bose premium sound system
B07 Pink Left rear door speaker + Standard radio
B08 Orange Left rear door speaker - Bose premium sound system
B08 Orange Left rear door speaker - Standard radio
Your C connector pin outs can be found on Richards
http://www.mercupgrades.com website unde FAQ.