This may seem an odd question, but is it possible in a 04-06 to downgrade from navi Gen. 4 to Gen. 3 by simply switching the navi unit in the trunk?

Why you may ask.

The reason is that in Europe there were no Gen. 4 maps for which reason the European 04-06 cars came with Gen. 3 navigation. It did, however, come with back-up camera.

So, if you bring a US 04-06 to Europe, there will be no maps for it, so you will have to down-grade to Gen. 3 to have working navigation.

I know the LS430 navigation is outdated, but a totally defunct navi screen makes even less sense.

 

It appears that Navilex can provide European maps for the U.S. market 2004-2006 LS430. A German friend has been satisfied with their service. Their website: http://www.navilex.hu/

 

Thanks a lot!

I would never have imagined that a Hungarian company with a Hungarian language only website would offer this service.
Very odd that a market to provide European maps for US Lexus/Toyota navigation systems do exist in Hungary and apparently not in any other European country. Also, very strange that their website is not in English or German.

This said, when you know how maps are coded according to a given format/generation for a given brand, I assume it is not rocket science to merge the format and the raw map data to make the discs readable in the given format.
Just strange that only a guy in Hungary decided to do so!