Rear door do not unlock

[andrewwynn]

Originally Posted by jdstrickland

You need Item 1, here, https://www.realoem.com/bmw/enUS/sho...diagId=51_7770



The Door Lock Actuator is a polarized thing, when the + and - are one way the actuator locks, the other way makes the actuator unlock. The lock and unlock coils can fail independently of the other, this would give you a lock that locks but won't unlock. The polarity of the power is decided by the body control module (there's a name for this item that I don't recall). It's also a possible variant that there are three wires to the actuator, and when wires 1 & 2 are used, the lock locks, and when 2 & 3 are used then the lock unlocks, the affect is the same, you can have an actuator that locks the door but will not unlock it.

(The diagram I gave you is from an '05, you should click the part number to pull up the cross reference list to see if the same part is used on your car.)

A bit of a distinction without a difference but that is not an accurate statement.

The lock and unlock is performed with the same motor that has voltage applied in opposite direction. For some reason however the brushes wear or whatever, The motor will stall in the unlock direction where it’ll still work in the lock direction near end of life. eventually it won’t work in either direction.

There are no coils involved in the lock mechanism other than I suppose a hall effect coil that is measuring the position of the lock.

Functionally the defect acts as described why I said A distinction without a difference