Passenger door central locking - sounds like a "machine gun"

[Mike_H]

Hi Folks, sorry for the poor subject title but couldn't think of anything else...my central locking has developed a strange noise when activated (all doors are locking/unlocking OK), but the passenger door actuator is making a noise akin to a little machine-gun (brrrrr) for a second or so sounding like its repeating the open/close movement - does anyone have any idea what it may be...I get the feeling its a sign of imminent failure of one of the components.

[steviebongo]

Sound's like the door solenoid on the road oot maybe.

[g8dhe]

Quite possibly, the actuator that operates the door has a switch built into it that operates at the end of its travel, and a relay coil then holds the switch open/closed until the opening/closing pulse has finished. It sounds like the switch is not opening at the end of its travel and you can hear the motor slipping. Sound like it would be a good time to acquire a replacement actuator whilst is hasn't yet burnt or worn out the plastic (?) gears in the unit !
The diagram below shows the three actuators the block to the left delivers the opening / closing pulse to operate all three of them.
http://www.g8dhe.net/bwm/bwmanualp.htm?1997/Page_108
Here is typical picture of there construction, not sure how it compares with the Mazda units but there will be some similarity! http://auto.howstuffworks.com/power-door-lock3.htm

[Mike_H]

Pulled the door lock out & inspected the solenoid - the ball screw style shaft has at some time sheered near to the drive gear & been repaired with a pin being inserted, this joint had broken & the shaft was continuing to rotate so the end of travel switch wasnt getting the correct signal hence the "Brrrrrrrr" as it tried to carry on locking - of to find a new solenoid mechanism now.