Need Help with Radio Wires

[rade30]

Hello, this is my first post here and I'm relatively new to e30s in general. I got my 1989 325i vert around a month ago and decided that I would get a new stereo head unit. I believe the car has non premium sound (it has the small tweeters by the mirrors) and there is no fader or anything besides the usual head unit for audio. The stock radio was a KE-83zbm, which has some weird connections that I cant seem to find much information about online. I eventually found the manual for it online and was able to figure out the ground, accessory, and memory wires and I have those set up and functional to the aftermarket harness. The problem I'm having is the speaker wires. I am able to define the front right/left and rear right/left, but the problem is there is only 1 wire coming for each. There is no negative and positive wire for each speaker coming directly out of the dash. I am just wondering if anyone is familiar with this and how I should go about it. Thank you!

Front Left----Yellow
Front right---Blue
Rear Left-----Yellow/Black
Rear right----Blue/Black

[AndrewBird]

If you have tweeters by the mirrors, you have premium sound. This means you should also have an amp in the trunk near the power antenna.

Read this:

https://www.r3vlimited.com/board/showthread.php?t=191119

Specifically: "you need to unwrap about 8" of fader harness to see if you have 4 pairs of speaker wires"

Unwrap your harness back into the dash and see if you have more wires. You will also need to bypass the stock amp in the trunk.