Frequently, questions about connecting the original radio have been coming up. I decided to address this gap.
Connector #1

Remote control connector. Can be left unconnected. The radio works without it.

Connector #2 (large blue-9 pins)

Pinout is below

Top row of contacts from left to right
1-red - front left speaker +
2-blue - front right speaker +
3-green with black stripe - power supply +12V from ignition in ACC position
4-not used
Bottom row of contacts from left to right
1-black - front left speaker —
2-white - front right speaker —
3-brown with white stripe - ground
4-not used
5-green - power supply +12V when parking lights are on

Connector #3 (white-5 pins)

Top row
1-yellow - rear left speaker+
2-pink - rear right speaker +
Bottom row
1-light green - rear left speaker —
2-green with red stripe - constant power supply +12V
3-purple - rear right speaker —

pinout of jacks
pinout of radio

and a few photos for clarity

Best of luck!
don't confuse polarity! (Both literally and figuratively!)