New Style of Door Key Barrel

[John Norman]

My door key turns through 90 degrees in each direction but doesn't lock or unlock the door. Fortunately my key fob and central locking are AOK.

I removed the key lock barrel and confirmed that the lock has suffered the mechanical failure described in many E46 Youtube videos. i.e. the tab on the metal plate under the spring had broken.

I use my physical key on a daily basis, leaving the key fob in the car while surfing. While researching the issue a local locksmith explained that the physical key is only meant for occasional or emergency use. The broken plate looks about as strong as a recycled Coke can! Shame on BMW.

I can't find an F32 lock repair kit for sale. Does anyone know if the relevant plate from an E46 repair kit will fit?

My other question concerns the design of this F32 style lock.

The E46 type has a lock shaft which has a "cross" shaped head that fits into the actuator socket within the door and signals the vehicle to unlock the door when turned. With the lock removed you can lock/unlock the door using a screwdriver in the actuator socket.

The F32 version has a toothed sprocket at the inner end of the lock barrel that engages with a matching gear wheel mounted on the carrier in the door.
Using the tip of a screwdriver to manually turn this gear wheel does not lock/unlock the door.

I'm baffled as to how a functioning key barrel actuates the actuator! Any clues??

[John Norman]

Update - I think I am now able to answer my own questions!

The right/left "top plate" from an E46 door lock barrel repair kit does fit.

As mentioned previously, manual manipulation of the gear wheel mounted on the lock carrier in the door doesn't lock/unlock the door. I did notice that there is a plastic moulding attached to the lock barrel that appears to have no function. I now suspect it contains a coded security chip that is checked by a "proximity reader" in the door lock actuator but only when it is mounted in the door.

Sure enough - when I replaced the broken "top plate" in the barrel and re-fitted it to the door - it worked like a charm.

NB I disturbed the position of the door mounted gear wheel while trying to figure out how the lock worked. I had to "re-centre" the gear wheel when re-fitting the lock barrel in order to allow the key to rotate through 90 degrees in each direction.