just bought 99 ml 430( no owners manual), dont know how to keep interior lights off when doors open/ what is the low range button for?

Low Range will set your transfer case to a taller gear ratio for added torque to the wheels.

A more important question is how to get an owners manual. Your dealer can order one for you, or call 1 800 FOR MERCedes and they can supply you with one, they're about $10.

Gilly

Owners Manual can buy off ebay as well.... Low Range I believe is used when Offroading, or when you lower a boat into the water.. etc...

Don't push the low-range button while moving or in-gear. You really need to read the owners manual. This is no chevy truck!

It doesn't really matter if you push it or not; if the parameters aren't met, it won't try to engage low range, it will just flash the low range light in the instrument cluster.

Gilly