95 lexus ls400 stereo wiring diagram

hi, i'm helping my friend install a pioneer headunit into his 1995 lexus ls400 would anyone happen to have the wiring diagram for this vehicle. i remove the stock deck already and the back has 3 harnesses attached to it. these don't look like the typical harness you see on toyota's. are those wires coming from a stock amp or are those wire the speaker wired and all i would have to do is just test and see which wire belongs to which speaker. his car has 2 mid and 2 tweets for the front rear doors have to mid and rear deck has 1 subwoofer. if there is a stock amp that this is hooked up to can you please tell me the location of this stock amp. or if anyone has a wiring diagram or some sort of information that will make my life work a bit easier please let me know thanks.

The factory amp is located on the right side of the trunk. I wish I had wiring information for you. You should be able to use the Metra 70-8112 harness for this vehicle as far as I know.