my interior light does not work on auto,but does work on manual also trunk light any ideas
No disrespect to Jayson, but that link he replied with seems to be about the climate control lighting. I believe you are asking about the interior "dome" lighting.
I had a similar issue with my 2001 SLK320 and determined it was a defective PSE unit. I could switch the lights on and off, but if left in the auto on position for automatic fade and shutoff, they would not work properly.
The PSE is notorious for corroded contacts at the connections rendering its "automatic" functions inoperable. I tried to clean the connectors but in the end had to replace it to get everything working properly.
Thanks to this forum, I learned about this common problem.
Here is additional info http://www.benzworld.org/forums/r170...fit-check.html
Hope you are able to clean yours and get it working!