Hi,
If you look below, I attached the wiring schematic for the basic stereo that came with the vehicle. I highlighted all wires related to the speakers.
If you follow them back to where they would attach to the back of the radio, you will see which are negative and which are positive. Also, the wire colors are included in the schematic, so you know which wire is which.
Let me know if this helps or if you have other questions.
Take care,
Joe
See pics below. Note: I had to cut the schematic in half to make it readable for you. I did overlap the two so you can follow from one to the next.
Images (Click to make bigger)
Saturday, January 15th, 2022 AT 5:47 PM