Jammed in gear

[swamprat]

I have 52 w210 240 which has recently occasionally started to lock itself into gear after overrunning down hill. You feel a hefty thump as the box changes down and afterwards the gear is locked in and even using manual shift does nothing. The only way to unlock the box is to switch engine off and restart which clears it.
Less than 500 miles ago I changed gearbox oil and filter hoping this would sort it
Local garage suggest new box of electronics in box at cost of £1500-ouch!
Any ideas please

 

[mattkh]

Less than 500 miles ago I changed gearbox oil and filter hoping this would sort it

Hi
Did you check the level at 85 degrees.

 

[brandwooddixon]

Sounds like it's dropping into Limp mode.
This will give you second and reverse.
It could be an electroplate problem, but a STAR diagnostic would tell you what's wrong.
Where abouts are you? Perhaps someone can recommend a good independent that you could use.

 

[malcolm E53 AMG]

As already said typical gearbox electrical plate symptoms mine did the same. Electric plate from MB and oil and filter change about £450 all in.

 

[television]

MB have this fault listed, and my 129 would do that, the cure and worth trying is to clean the ECU connector plug on the box,,, the end CAN connections carry no current and they can lose contact, just try a good squirt of non drying switch clean from Maplins. This has fixed 3 cars on here so far but no all, and easy to try.

 

[swamprat]

MB have this fault listed, and my 129 would do that, the cure and worth trying is to clean the ECU connector plug on the box,,, the end CAN connections carry no current and they can lose contact, just try a good squirt of non drying switch clean from Maplins. This has fixed 3 cars on here so far but no all, and easy to try.

Thanks all, for the comments and suggestions
I will try the switch clean first and see how it does