The aux input has definatey been done:
Factory Radio Service aux-in on 2000 LS400 - Page 3 - ClubLexus - Lexus Forum Discussion
It also mentions some sort of isolator to get rid of hiss
Hi
I had this problem on my 430 - I purchased new bulbs bu that mae no difference - turned out to be the ballast - IIRS your car Xenons - could this be the ballast?
On the 430 the ballast is secured to the under side of the headlight
hope this helps
Hi
I would
(a) Get the battery checked - a failing battery can cause this
(b) check nothing metalic is in the armrest like keys or loose change
hope this helps