MBArne

Hi,

I have an S500 (V8 5,5L) with the 7G Tronic Transmission and randomly it locks in a gear.

This happens especially when cruising on a highway in about 80-100km/h. When I slow down, the transmission could lock itself in a high gear (5-7), and I would need to stop > set it in "P" > turn off the car > and on again to make it function normally.
The manual gear change doesn't work either, I actually need to "boot" the car..
This is quite annoying, and could also cause an accident (as you would expect to have good acceleration from standing still etc., but not in gear 5-7 after a turnoff).

Anyone have any experience with this?

Thanks,
Arne

alx

quite common.

either your conductor plate is quitting or your valve block is quitting. both are inside the transmission. easy to remove and replace, but your car needs to be read with star/das and determined which one of the above is at fault.

normally if you need a new conductor plate/ valve block the work needs to be done at a dealer or indy with legitimate star/ das because coding is required for the replaced part. there are also other ways (repair the conductor plate so no coding is required), but you need to send your part out to a vendor.

triniexr

ah boy... here we go again.. take it to the dealer or get an indy to check it out...

I can see I'VE HAD IT! 2007 S550 STUCK IN FIRST GEAR PT2 starting.......

MBArne

Thanks a lot for your responses.
I will send it to a dealer then, hope it's not too expensive to fix

Cheers,
Arne

Jason B

Get a quote from your dealer and and then try to find an independent shop to fix it. It will most likely be half the cost of the dealer.

Prochambers

Hopefully not!

gerrooney

I had the same problem with my e 270 cdi recently so I removed the gear selector unit opened it up to see if there was anything amiss with the electronics and I noticed that there is about one third of the gear selector sits below the car and is exposed to the cold whereas the top half of the selector is inside the car and this got me thinking about condensation building up on the board so before I put it all back together I sprayed the board and all other electrical contacts with circuit cleaner and wd40 to keep the moisture away I also insulated the rubber that covers the unit outside the car,and guess what I have been trouble free for the last 5 days whereas I was having to stop and start the car 20 times a day before any of this ,just to add i had done the gear oil and filter the week before and it did nothing for the problem even tough the gear oil was black coming out so it did need to be done,best of luck to anyone with this problem as some of the answers I have seen about this intermittent proble can cost big bucks,I would do the oil and filter then take out the selector and do that long before I would go near MB or an indie,

DaveW68

That is probably the most informative thread of the past year. So much help was offered to the OP and there was so much to be learned from the wealth of information offered by all of the contributors, especially Mike.

Prochambers

It probably was but it had some way off topic comments too!!!

triniexr

LOL!!!!!