Overview, Remove/Install Backrest Lock on Front Seat

Preliminary work:
Front seat removed. [1][2]Procedures
Side covering on backrest frame removed.
Rear covering on backrest removed.
Side covering on outside of seat cushion frame removed. [1][2]Procedures






Inside of seat

Covering (1)
press off and remove.

Connector (S52/2x1)
disconnect.

Wire to microswitch (S52/2)
expose.

Retainer for electrical wires
unscrew and remove.

Flexible drive shaft for backrest adjustment gear on front seat
remove.

Screws on motor (M25m5) for backrest adjustment
unscrew (4 each).

Toothed belt on backrest gear
release tension and remove from gear pulley.

Control cable (2) on backrest lock
unhook.

Retainer and plastic washer on backrest hinge bolt, inside
remove.

Screw on backrest gear, inside and outside
unscrew (2 each, 12 Allen wrench). Observe installation note!

Backrest lock (4) with gear on backrest hinge bolt
actuate release lever on lock and remove.

Clamping pin for gear spindle
remove (diameter 3 mm)

Gear spindle on backrest lock
unscrew and remove gear.

Gear spindle in backrest lock
screw in until clamping pin can just be knocked in.

Clamping pin for gear spindle
install (overall length 30 mm).

Backrest lock with gear
position and fasten to backrest hinge bolt with plastic washer and retainer.

Screws on gear inside and outside
screw in, 35 Nm. Observe installation note!

Control cable (2) on backrest lock
hook in.

Backrest lock
adjust.

Both gear spindles with flexible drive shaft
screw in all the way up against the stop.

Backrest lock
check, both locks must catch simultaneously and completely.

The backrest lock adjustment
can be corrected by turning the gear drive shaft slightly, for this purpose use flexible drive shaft.

Both control cables for the backrest lock
must be adjusted with play of 0 to 1 mm.

Toothed belt
install and tighten, do not turn gear drive shaft.

Both gears with drive shaft
connect and fasten drive shaft with retainer on backrest frame without changing previously adjusted backrest lock.

Backrest lock
check with the two microswitches (S52/1) and (S52/2).

Connect measuring instrument to connection board (X55/3)
and check both microswitches individually.

Backrest
locked: Nominal value < 1 Ohm
released: Nominal value infinity Ohms
Continue to reinstall in opposite order.

Outer side of seat
Connector (S52/1x1)
disconnect.

Wire to microswitch (S52/1)
expose.

Flexible drive shaft for backrest adjustment gear
remove.

Screws on backrest gear inside and outside
unscrew (2 each, 12 mm Allen wrench). Observe installation note!

Retainer on backrest hinge bolt
remove.

Backrest
release and tilt forward.

Bolt on backrest hinge
pull out until lock with gear can be pulled down slightly.

Control cable (3) on backrest lock (5)
unhook.

Backrest lock (5) with gear
remove.

Clamping pin for gear spindle
remove (diameter 3 mm, length 37 mm).

Gear spindle on backrest lock
unscrew.

Backrest lock
remove from gear.

When installing retaining cable (6) for front seat backrest
attach to inner screw of backrest gear to allow motion.

Reinstall in opposite order. Before installing the flexible drive shaft, check the adjustment and function of the backrest (see backrest lock - inside of seat).

Installation note
The thread on the gear screw is micro- encapsulated and must be replaced after removal or coated with screw securing agent.
Tightening torque: 35 Nm.
Check function of automatic locking system (Testing and Inspection, items 10-13).