I ordered the Pioneer fit kit (86100-0W080) and the XM receiver (86180-0W032) for the 2008 GS. Had it professionally installed. They told me that while the headunit radio screen detected the radio, and provided the text info, absolutely no audio was coming out. They did not think there was anything wrong with my internal wiring. I have the sharkfin antenna. They said that in the fit kit, the wire to the amp "didn't fit." I don't have ML. I have the "Lexus Premium Sound System" which I assume is the Pioneer. The fit kit parts I got are allegedly for the Pioneer, not ML.

The only other thing I can think of is the manual said the part number for the XM receiver is actually 86180-0W031, but research on the internet shows that part number ending in 32 replaced it.