The ignition lock cylinder of E31, E36, E38 and E39 models was designed with an actuating tab that breaks off if someone forces the lock with the wrong key or some form of tool as part of a vehicle theft effort.
The purpose of the breakaway tab is to prevent the lock assembly from being forced to the point where the cylinder breaks out of the housing, allowing the steering lock to release and the ignition switch to be turned with a screwdriver. Since the cylinder will spin freely, the required force cannot be applied to the assembly.
It is possible to break off the tab if enough force is applied to the proper key, and the key has not been inserted completely into the cylinder.
Even if the tab has been broken off, the lock will still operate, as long as the correct key is completely inserted into the lock.
If the tab has been broken off, the lock cylinder can be replaced, following repair manual instructions, Section 32 32 050. When the cylinder is removed, carefully inspect the inside of the housing to locate the tab, and remove all broken-off pieces. It is normally not necessary to replace the housing unless damage to the inside of the housing is evident.
For additional information, visit www.alldata.com.
Technical service bulletin courtesy of ALLDATA.