Hi! my central lock remote control stop working????I do not know or it is receiver ,or it is remote control???I put new battery but it is not helping!

 

Same here. Replaced batteries in both keys. Synchronising keys doesn't help.

BUT, it works sometimes!

When I unlock the car with the key in the lock all door unlock.
If I lock the car with the key in the lock only the drivers door locks.
I can lock and unlock the doors with the central locking switch inside the car.

Any ideas please?

 

you should repost in the W163 section of this forum. Your '99 MLs are both model W163, not W164.

https://mbworld.org/forums/m-class-w163-10/