snowybunting

I bought this car new in Dec 2019. It's my daily car, I have 72k miles on it, have had no issues until recently. After I've driven the car for a while - at least 20-30 minutes - and shut it off to go into a store or something, when I restart the car it will not go into "D"rive. I drop the shift lever, it hits the "D" then goes right up into "N"eutral. At this point it doesn't matter if I try putting it back into "P"ark or drop back into "D" from the neutral position, it won't go into drive. I have to play with it for a minute or two, and when it *does* finally go into "D", it drops/clunks really hard into 3rd gear. At that point, I can't force it into 1st or 2nd even if I go into Manual mode until I've shut the car off for at least 15 minutes. It will go into reverse when this is happening, but I can't get to D from reverse either. Recently I've noticed the engine light comes on when this is happening, but it doesn't stay on all the time. This doesn't happen every time I've driven it for a while, only about 25% of the time.

I'm making an appointment with the service department, but thought I'd see if this was something someone else has come across.

Isawelvis

Probably rear auxiliary battery.

snowybunting

They have had it in the service department for 5 weeks now. I can't imagine why it would be that battery, but I don't pretend to understand how the system works so maybe I'll ask them to check that out.

Can you explain why that battery would affect gear change please?

snowybunting

Actually, I used the Google and saw for myself. Thank you for the pointer in the right direction.

snowybunting

Just a quick update, the car is still in the service department (2 months now) and they cannot figure out what is wrong. They dismissed the rear aux battery suggestion, and have dropped in 3 different auto transmission valve bodies but cannot get the software to work with any of them. Apparently they are trying to contact engineers in Germany to assist, but from what I've been told this hasn't happened yet. I have some feelers out at other Mercedes/foreign car shops to see if anyone has any ideas, but so far I'm striking out. I asked them to just give me the car back until they can get someone in their dealership who can get it running, but I've been told the car is undriveable now as they can't even get that old valve body working.

All the news isn't bad though, I get to drive around in a rental they've given me, a 2022 GLC 300. It had 1050 miles on it when this started, there's 5400 on it now. It's white, and I feel like a soccer mom driving it.