721955 Replacing backrest frame

WM 721955 Replacing backrest frame

Technical values





Preliminary work

1. Remove cushion carrier for front backrest. -> 722419 Removing and installing cushion carrier for front backrest - section on "Removing" 722419 Removing and installing cushion carrier for front backrest (air-conditioned comfort seat)

Information

Only for vehicles with lumbar support.

2. Remove control valve for lumbar support adjustment. -> 723319 Removing and installing control valve for lumbar support adjustment - section on "Removing" 72331900 Removing and installing control valve for lumbar support adjustment

Information

Only for vehicles with lumbar support.

3. Remove lumbar support. -> 723419 Removing and installing lumbar support - section on "Removing" 72341900 Removing and installing lumbar support

Information

Only for vehicles with lumbar support.

4. Remove motor for lumbar support. -> 723619 Removing and installing motor for lumbar support - section on "Removing" 72361900 Removing and installing motor for lumbar support

Information

Only for vehicles with adaptive sports seats.

5. Remove air cushion for backrest. -> 721719 Removing and installing air cushion for backrest - section on "Removing" 72171900 Removing and installing air cushion for backrest

Disassembling backrest frame

Removing foam part

1. Remove foam part -1- at the headrest.





Taking off foam part

Removing supports for backrest side parts

1. Unscrew fastening screws -1- and remove support for right backrest side part -2-.





Removing support for right backrest side part

2. Unscrew fastening screws -1- and remove support for left backrest side part -2-.





Removing support for left backrest side part

Removing inner spring on backrest frame

1. Disengage tension springs -1- at left and right on inner spring -2- ( -arrows A- ).





Removing inner spring on backrest frame

2. Unclip inner spring -2- on backrest frame at the drive shaft -arrow B- and remove inner spring.
3. Disengage tension springs -1- on the backrest frame.

Disconnecting wire harnesses on backrest frame

Information

Only for vehicles with lumbar support.

Information

Make sure not to trap or damage the wire harness when pulling it through.

1. Pull wire harness for backrest -1- down out of the backrest frame -2-.





Pulling out wire harness for backrest

2. Turn plug connection -1- approx. 90° anti-clockwise -arrow A- and pull it off the backrest frame -arrow B-.





Disconnecting plug connection

3. Release plug connection -arrows C- and disconnect it -arrows D-.

Information

Make sure not to trap or damage the wire harness when pulling it through.

4. Press locking tabs on fixing clip -2- together and unclip it -arrow E-. Pull wire harness for backrest -3- down and out -arrow F-.
5. Press locking tabs on fixing clip -2- together and unclip wire harness for side airbag -4- from the backrest frame -arrow G-.

Removing frame for side airbag

1. Unscrew fastening screws -1- and unclip frame for side airbag -2- from the backrest frame -3-.





Removing frame for side airbag

Disassembling backrest frame

1. Remove fastening nuts -1- from the backrest frame -2- , check them and replace if necessary.





Removing fastening nuts

2. Unclip fixing clips -1- from the backrest frame -2- , check them and replace if necessary.





Removing fixing clips

Removing backrest frame

Information

Two persons are needed to remove and install the backrest frame.

1. Secure backrest frame -2- in upright position.





Removing backrest frame

2. Unscrew fastening screws -1- on left and right and remove backrest frame -2- up out of the seat frame.

Assembling backrest frame

Installing backrest frame

DANGER

Loosen the safety screws.

- Danger of injury if front seat is not screwed down correctly.

-> Always replace fastening screws for the front seat after customer service and reworking.
-> It is not permissible to make alterations to the micro-encapsulated screws (e.g., use lubricant, loosen bolts, and screw them down again).

Information

Two persons are needed to remove and install the backrest frame.

1. Fit backrest frame -2- into the seat frame, position it correctly and secure with the fastening screws -1-. Tightening torque=> Tightening torque: 34 Nm (25 ftlb.)+/-4 Nm (+/-3 ftlb.)





Installing backrest frame

Assembling backrest frame

1. Press in fixing clips -1- on the backrest frame -2-.





Pressing in fixing clips

2. Screw fastening nuts -1- onto the backrest frame -2-.





Screwing on fastening nuts

Installing frame for side airbag

1. Clip frame for side airbag -2- to backrest frame -3- and secure with the fastening screws -1-.





Installing frame for side airbag

Securing wire harnesses on backrest frame

Information

Only for vehicles with lumbar support.

Information

Make sure not to trap or damage the wire harness when pulling it through.

1. Pull wire harness for backrest -1- up into the backrest frame -2-.





Pulling through wire harness for backrest

2. Press fixing clip -2- on wire harness for side airbag onto the backrest frame -arrow A-.





Securing wire harness for backrest

Information

Make sure not to trap or damage the wire harness when pulling it through.

3. Pull wire harness for backrest -3- through -arrow B- and press in fixing clip -2- ( -arrow C- ).
4. Push plug connection -1- together -arrows D- until it engages securely.
5. Insert plug connection -1- into the backrest frame -arrow E- and turn it clockwise by approx. 90° -arrow F-.

Installing inner spring on backrest frame

1. Engage tension springs -1- in the backrest frame.





Engaging inner spring on backrest frame

2. Clip in inner spring -2- on lower part of backrest frame at the drive shaft -arrow A-.
3. Engage tension springs -1- in the inner spring -2- on the backrest frame -arrow B-.

Installing supports for backrest side parts

Information

Observe hose routing!

In vehicles with lumbar support, make sure the hoses are routed correctly in the area of the backrest side support.

1. Insert support for left backrest side part -2- and secure with the fastening screws -1-.





Installing support for left backrest side part

2. Route wire harness for side airbag -1- as shown behind the backrest side part support -2-.





Routing wire harness for side airbag

Information

Observe hose routing!

In vehicles with lumbar support, make sure the hoses are routed correctly in the area of the backrest side support.

3. Insert support for right backrest side part -2- and secure with the fastening screws -1-.





Installing support for right backrest side part

Fitting foam part

1. Fit foam part -1- to the headrest.





Fitting foam part

Subsequent work

Information

Only for vehicles with adaptive sports seats.

1. Install air cushion for backrest. -> 721719 Removing and installing air cushion for backrest - section on "Installing" 72171900 Removing and installing air cushion for backrest

Information

Only for vehicles with lumbar support.

2. Install motor for lumbar support. -> 723619 Removing and installing motor for lumbar support - section on "Installing" 72361900 Removing and installing motor for lumbar support

Information

Only for vehicles with lumbar support.

3. Install lumbar support. -> 723419 Removing and installing lumbar support - section on "Installing" 72341900 Removing and installing lumbar support

Information

Only for vehicles with lumbar support.

4. Install control valve for lumbar support adjustment. -> 723319 Removing and installing control valve for lumbar adjustment - section on "Installing" 72331900 Removing and installing control valve for lumbar support adjustment
5. Install cushion carrier for front backrest. -> 722419 Removing and installing cushion carrier for front backrest - section on "Installing" 722419 Removing and installing cushion carrier for front backrest (air-conditioned comfort seat)