My single button remote with the folding slab key has recently stopped locking my car. I tried the synchronizing method mentioned on other posts but that did not help. I have gone through a series of tests and was wondering if anyone can diagnose the problem:

1) pointing the remote at the rear view mirror and pressing the remote button, the red light blinks on the mirror a click is heard the alarm arms itself but the door locks to not lock.
2) pressing the remote again a click is heard , green light on mirror flashes the alarm disarms.
3) using the slab key in the passenger door which is the only door with cylinder, the passenger door locks a click is heard and the alarm arms itself no other doors lock.
4) using slab key again the alarm goes out and passenger door opens.
5) pushing all locks down manually and then using the slab key to lock passenger door all doors are now locked and alarm is armed.
6) using the REMOTE to open the doors by pointing at the mirror BOTH FRONT doors now open and the alarm disarms. The back doors do not unlock.

Any help would be appreciated THANKS Rod

PROBLEM SOLVED, after rechecking the yellow tubes at the vacuum motor I found one of them off. Dont know how I missed it the first time but, I did. One of the end tubes had worked its way under the door sill and never saw it..............

Where is the vacume pump and where are lines connected to at the door. It sound logical but do nt know where to look for the compoents.
Thanks for your help,
Ron

Pump is under the rear seat, right side, next to the battery (if it's the same as my '96).

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970