Well, took car to sister dealership for a fresh perspective, and to add to the new trans computer, they diagnosed it as a problem in the shifter itself. So, I got a new "floor shift mechanism" and "selector module."

But when I drove it off the lot, it did the same thing!

I brought it back inside, where I noticed someone had also hit the car against something on the back lot apparently, causing a bend on the rear-door pillar by the quarter glass. They did light body and paintwork to it - ugh - but it looks fine now, and I'm ok as long as they didn't have to paint the whole panel.

Anyway, the foreman himself worked on the car, and found a loose screw on the shift rod at the transmission - so, for a loose screw, I got a new TCM, shift mechanism, selector module, and 3 qts of trans fluid (and some light body damage)

In their defense, my shop guy said he had NEVER seen this happen before, and has no idea how the screw became loose.

SO, the loose screw was causing the lever to not seat into "D" fully, and because the shifter was out of position and moving ever so slightly while I was driving, confusing the electronics.

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former: 83 300D, 97 C230, 93 400E

current: 08 C300 Luxury , 92 500SL