Quick disclaimer, I'm actually on a RX300. I made a custom harness to retrofit an OEM system into a non-nav car. It's working but I think I just have some bad parts. I'm running a Gen 4 nav drive which definitely is compatible based on the experiences of others.This part # is shared with 05-07 330/350/400's

I think the nav drive is shot, though, based on a few symptoms. One that I'm trying to triple check isn't wiring-related is the turn by turn.

When the nav unit attempts to send audio (either turn-by-turn or by setting audio level on the multidisplay) it mutes the 4 door speakers (not the sub) and doesn't produce sound. Then it unmutes and everything works fine.

Has anyone ever experienced this? Thanks in advance.