Are you trying to bypass the factory amp? I installed a new head unit and replaced speakers (front door/rear gate) in my D2.
Handy trick: once you think you've found the correct wires going to the speakers (coming out of the amp), grab a 9 volt battery. Connect a wire to each terminal. Connect one wire from the battery to one wire going to the speaker. Tap the other two wires together. You'll hear a crackle from the speaker if you have the correct wires.
I found it much easier to run wires from the head unit to the amp vs. attempting to put in a new run all the way to the speakers.
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