Front Door Latch: Service and Repair

51 21 090 Removing And Installing/Replacing Door Lock In Left Or Right Front Door

Special tools required:







Necessary preliminary tasks:
- Remove rear section of power window.

Driver's side only:
- Remove cover on outer door handle







Disconnect Bowden cable at bottom (1) and top (3) from door lock (2).
If necessary, release cable clip on door lock (2).

Installation note:
Bowden cable must be correctly engaged in locators in door lock (2).

Bowden cable must be laid without kinks in bend to door lock (2).
Seal (4) must be correctly fitted on Bowden cable.

IMPORTANT:
Door cannot be opened if Bowden cable (1) is incorrectly laid.







Unclip locking rod (1).
Unlock and disconnect plug connection (2) at tabs (3).







Version with Automatic Soft Close system:
Disconnect plug connection (1).
Unfasten screws (2).







IMPORTANT:
Do not damage door lock seal when removing.

Release screws (1).
Remove door lock (2) from inside.

IMPORTANT:
To avoid leaking and electrical malfunction:
Pull door lock (2) with special tool into corner (3), refer to illustrations R51381 and R51594.







Installation note:
Gasket (1) on door lock (2) must not be damaged.
Adapter switching socket (4) must be correctly engaged.
Door wiring harness must be correctly laid in guide (2).







Installation note:
Version with Automatic Soft Close system:

Make sure Soft Close Automatic drive (1) is installed in correct installation position. Control line (3) must not be twisted around Bowden cable (2).
Make sure control line (3) is correctly laid in guides (4).







Installation note:
- Install door lock and insert screws (1), do not tighten down.
- Slide special tool 51 2 190 into opened rotary striker until striker engages in first stage







Installation note:
- Pre-tension door lock (1) with knurled screw (2) until special tool 51 2 190 just contacts corner points (3)

IMPORTANT:
To tension door lock (1), it is only permitted to turn knurled screw (2) by a further 1 to 1.5 turns (max.) (risk of damage).
Door lock seal must rest uniformly on inner door panel (water ingress).

- Tighten down door lock screws, tightening torque 51 21 1AZ.