1996 E320 Key Fob Will Not Synchronize
 

I have two key fobs .. one is synchronized and the other is not. When I hit the big button on one of my key fobs both the red and green lights under the rear view mirror flash for 30 seconds. I checked the batteries ... they were ok .. I tried synching per the manual .. nothing. I changed the two batteries .. tried again .. nothing. I stood outside the vehicle and pressed big button twice, then within 30 seconds opened the door and then inserted the key to position two on the ignition switch ... per the manual .. nothing. Fob did not synch.

Does anyone know how to synchronize the key fob on the infra-red 96'E320 -- frustrated in FLorida ...carlos

How did you check the batteries? Both lights flashing always indicates low batteries.

Checked and Replaced Batteries
 

To check batteries I held down the big button .. and saw the led light on the fob light on - like it says in the manual. I replaced the two batteries and still when I try to sync per the manual ... nothing.

I'm not sure if this is the first time you've had to synch or not, but the way I did it recently is to actually sit in the driver's seat and point the fob at the mirror. Press twice, with a distinct pause in between (not like double-clicking a mouse), then switch to position 2, pause, then start the car.

I'll try it inside
 

I'll try it inside -- thanks.

Key fob will not stay synchronized
 

Our '96 E300D has two identical key fobs. One works fine, the other keeps losing its synchronization. When the "bad" one loses sync, I follow the procedure in the owner's manual – just as post #4 says – and then it works again for awhile. I swapped the pair of 3V batteries between the two fobs and checked them with a meter, they test good. The "battery test" (press the button for 1+ second and the red LED will blink) works.

This is not a major problem since we have a second fob and since the metal key works regardless; nonetheless it would be nice to have this thing stay in sync without buying another as they are expensive ($140 last time I checked).

Jeremy