My remote no longer activates the lock/unlock. Yes, the batteries are fine. I even replaced them with new and no change. Upon using the key in the door nothing changes on the mirror-located red/green. On my '92 w140 using the key in the driver's door changes the lock color from red to green and vise-versa. I honestly don't remember if this is the case with the C220, but I think it was. If that is the case then it appears that the receiver end of the system is defective I checked the fuse for remote locking and it was fine. What could be the culprit here? How do I test the receiver end of the system?

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1996 SL320 97K miles
1996 C220 130k miles
1992 500SEL 170k miles <---sold
1986 300E 216k miles <---sold