my 320 CLK is 16 years old & have no service history , id like to replace the battery/s in the remote , but is it DIY or does it require reprograming after fitting ?

 

I have a 2001 S600. When I use the remote to unlock the doors, only the driver's door unlocks. I've tried using the remote to unlock then lock the doors then using both lock and unlock at the same time for 7 seconds. This was also the answer on Youtube. The mechanic was unsure of how to correct the problem. He forgot the steps. I still can only unlock the driver's door. Any suggestions<

 

I eventually went to library looked in wkshp manual to replace batteries .. A freind who had a later mrc said if remote batteries get low it causes all sorts of problems . If it wont unlock from 6 ft away then they are weak . locks actually work by vacumm remote just sends signal .