[what is the female connector with round shape on Eclipse ESIV Model 5441i]

Hi I purchased an ECLIPSE ESIV Model 5441i  few days ago and it works fine but

this one does not have Aux Code input.

I watched how people do  add the Aux  to old Car Audio on Youtube.

but I want to connect it to the few wires  in the round connector(this one has 12 pins)

is there any way to figure out the individual pins? I looked up the manuals on google , unluckily, I could not find one cause the unit is too old.

thanks in advance.