QUICKSHIFT

Have been having MAJOR problems with the starter since having it rebuilt by a reputable re-builder. Long story short, after multiple attempts to correct the problem of solenoids burning out and sticking, he finally walked away from it and suggested that if it happened again, to buy an actual re-man directly from MB. The starter started acting up on my wife yesterday. First it would "wing" when she let go of the key. The next time it wouldn't disengage at all unless she repeatedly hit the key (she knows her way around cars pretty good). She brought it home, parked it the garage and told me the starter solenoid had a mind of it's own. After sticker shock on starter's from MB even with my discount, I found a low KM one from a wreck about an hr away. I was going to pull it out of the garage if I could get it started, and change it in the drive way rather than take it out to my shop. It started fine so I went to put it reverse and the starter engaged! I put it in P and it stopped. Put in R and it engaged again so I put it in N, then D etc. Went back to R and again it engaged.
Just for fun, I shut it off and placed it in P. Then I turned the key to IGN stepped on the brake and pulled it into R......it started!
Now my question is, is the reverse lighting ckt connected to the start ckt for some reason? I don't think so. I even checked the K40 board ( I think that's what it's called) for signs of burning, corrosion etc and it looks perfect.
One other thing. The "check electronics" warning lit up in the display but only once. PLEASE HELP as my wife absolutely loves her BENZ!
PS: A new battery was installed at the same time and load tested several different times to rule out a defective battery.

Plutoe

Sounds like you not only have a very bad starter rebuild, but you have may a bad transmission gear selector switch and or the shifter rod is not adjusted correctly(bad bushing). Put the car on the lift and start the process!!