Central Locking System
Fixing the Double Lock Issue
The mismatched GM will cause miscommunication between the module and central locking system. This will cause GM to unlock the doors after you attempt to lock them with a remote. The quick fix is to replace the GM with a unit that pairs with your car.
See the service bulleting below for part numbers:
Repeating the first command then results in carrying out that command (e.g., try to lock again, and locking is now carried out). This function ("Asynchronous Position") is omitted in the new GM for all E32 models and E34 models prior to 9/91 (P/N 61358356095), and remains in the new GM for E34 models after 9/91 (P/N 61358355812) only for central locking commands "lock" and "double-lock".
If the doors were unlocked due to crash sensor activation, the locking command must be reactivated by double-locking with the master key from either the driver's or passenger's door.
After manually locking or unlocking the system, the door locks may become unsynchronized. To synchronize the locks, close all doors, trunk lid, and tailgate. Lock the passenger door by turning the key clockwise into the emergency locking position (approximately 110 degrees from position O). Unlock the driver side door. If any of the locks do not operate, repeat the locking procedure until the locking system is synchronized.
This procedure can also be used if the locks become unsynchronized. This might happen if a door which is not completely closed is locked, or a door handle is lifted before the interior lock button is raised.