Mercedes-Benz Parts Catalog Mercedes-Benz Accessories Catalog Mercedes-Benz Technical Articles Mercedes-Benz Tech Forums
 
Follow Pelican Parts on Facebook Follow Pelican Parts on Twitter Follow Pelican Parts on Instagram Follow Pelican Parts on YouTube Follow Pelican Parts on Pinterest Follow Pelican Parts on Tumblr
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
 >  >
Door Lock Actuator Replacement
 
Bookmark and Share

Pelican Technical Article:

Door Lock Actuator Replacement

Steve Vernon

Time:

1 hour1 hr

Tab:

$15 to $125

Talent:

**

Tools:

8mm socket, flathead screwdriver

Applicable Models:

Mercedes-Benz W123 (1977-85)

Parts Required:

Actuator(s)

Hot Tip:

Preform the work on a level surface

Performance Gain:

Doors lock correctly

Complementary Modification:

Detail the interior

The central locking system on the W123 is run by vacuum. Mercedes used this system early in their cars because it was more reliable and cheaper than early electronics. While most people get intimidated by the system, it is relatively easy and simple once you understand it. There is a vacuum pump on the front of the motor that makes vacuum for the locking system along with a vacuum tank in the trunk. The tank in the trunk stores enough vacuum for approximately 10 lock/unlock functions with the car off and then the locks will have to be opened manually. The door actuators are connected to the main actuator in the driver side door by a series of hard plastic vacuum lines. These lines can crack, leak and break as they get older, so you should inspect the lines both visually and with a hand vacuum pump before replacing the actuator. Even if the central locking system fails the doors can individually be unlocked or lock manually.

Over the years your car may have been serviced by multiple people including previous owners and this can lead to parts replaced with different size fasteners and hardware. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches. If something is different on your vehicle please let us know and share your info to help other users. If you have any questions or comments or even a different procedure you would like to share please leave it below and please leave your vehicle information.

Begin by parking the vehicle on a flat and level surface; there is nothing worse than trying to work on your doors while they continue swing open or closed.
Figure 1

Begin by parking the vehicle on a flat and level surface; there is nothing worse than trying to work on your doors while they continue swing open or closed. You will need to remove the door panel and plastic weather shield to access the actuator so please see our article on door panel removal.

With the door panel and plastic vapor shield removed, you can see how the actuator located in the lower section of the door (red arrow) is connected to a rod (purple arrow) that runs to the door latch and lock (yellow arrow).
Figure 2

With the door panel and plastic vapor shield removed, you can see how the actuator located in the lower section of the door (red arrow) is connected to a rod (purple arrow) that runs to the door latch and lock (yellow arrow).

The actuator is attached to the lower inner door skin (red arrow).
Figure 3

The actuator is attached to the lower inner door skin (red arrow). There will be two hard vacuum lines that run inside the lower door, out of the way of the window and regulator that supply vacuum to the actuators.

There have been several designs of actuators over the years but they all work in the same manner and on the same principles.
Figure 4

There have been several designs of actuators over the years but they all work in the same manner and on the same principles. Remove the connecting rod from the actuator by unclipping the tab on the top and removing the rod (red arrow) This will be used for adjusting the height of the rod to make sure the lock unlock functions with the actuator in the full up and down position.

The rubber connecters from the vacuum lines to the actuator can get stuck on if they have been there awhile, so use a flathead screwdriver and gently pry them off the actuator (red arrow).
Figure 5

The rubber connecters from the vacuum lines to the actuator can get stuck on if they have been there awhile, so use a flathead screwdriver and gently pry them off the actuator (red arrow).

Use an 8mm wrench or socket and remove the two mounting screws.
Figure 6

Use an 8mm wrench or socket and remove the two mounting screws.

Remove the actuator from the door.
Figure 7

Remove the actuator from the door. A good way to test the actuator is to cover one of the ports with your finger and try and lift up or push down the section that connects to the rod (red arrow). With one port blocked you should only be able to pull up and the other push down. If you can both push down and pull up with a port covered the actuator is bad. Installation is reverse of removal

Bookmark and Share

  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    

 

[Home] [Customer Service] [Shopping Cart] [Project/Wish List]
  [Privacy Statement]  [Contact Us] [About Us] [Shipping] [Careers]

Copyright © Pelican Parts Inc. -    DMCA Registered Agent Contact Page

Page last updated: Fri 12/9/2016 03:02:40 AM