AR42.46-P-0020R Remove/Install Brake Operating Unit (BOU)

Remove/Install Brake Operating Unit (BOU)
- with Sensotronic Brake Control (SBC) [model 211]

Shown On Model 211:

DANGER:
- Risk of injury, body parts may become jammed or crushed. Risk of injury, skin and eyes may be injured due to brake fluid spraying out at high pressure when working on the SBC brake system
- Deactivate SBC brake system using STAR DIAGNOSIS.
- Risk of poisoning from swallowing brake fluid. Risk of injury from brake fluid coming into contact with skin and eyes.
- Pour brake fluid only into suitable and appropriately marked containers. Wear protective clothing and eye protection when handling brake fluid.

1 Deactivate SBC brake system using STAR DIAGNOSIS.

CAUTION: See notes on repairs to brake system

2 Remove cover (1)
- Model 211

3 Disconnect electrical connector from brake fluid indicator switch (S11)
4 Draw off brake fluid from brake fluid reservoir (2)

CAUTION:
- Installation: Check correct assembly of brake fluid reservoir (2). No brake fluid should escape from the seals (6) in order to ensure satisfactory function.
- See notes on handling brake fluid

5 Disconnect SBC return line (3) from the brake fluid reservoir (2)

CAUTION: Before opening the SBC system, thoroughly clean the area surrounding the separation point. Even the smallest particles of dirt, introduced into the hydraulic components, can lead to malfunctions and a total failure of the SBC system.

6 Disconnect SBC feed line (4) from brake fluid reservoir (2)

NOTE: Collect any brake fluid which runs out in a fluff-free, absorbent cloth and seal connections with blind plugs

7 Unscrew bolt (2a) for securing brake fluid reservoir (2) out of brake operating unit BOU (5)
8 Pull brake fluid reservoir (2) out of brake operating unit BOU (5)
- Check seals (6) and replace if necessary.

CAUTION: Installation: The seals do not have any collar (6) and can be pressed out of the brake operating unit BOU (5) during the assembly of the brake fluid reservoir (2).

NOTE: Installation: Position brake fluid reservoir (2) vertically on brake operating unit (BOU) (5), pressing in the front and rear seal (6) at the same time.

9 Disconnect electrical connector of SBC pedal value sensor (B37/1)
10 Detach brake lines (7) from brake operating unit BOU (5)

NOTE: Collect any brake fluid which runs out in a fluff-free, absorbent cloth and seal connections with blind plugs

11 Remove left cover below instrument panel
12 Remove stop lamp switch (S9/1)
13 Remove clutch pedal switch (S40/3)

NOTE: Press locking detent and turn clutch pedal switch (S40/3) 90 degrees to the right.

14 Unclip cover (8) on brake pedal
15 Unscrew stud (9) from brake pedal
16 Unscrew nuts (5a) from brake operating unit (BOU) (5).
17 Remove brake operating unit (BOU) (5)
18 Install in the reverse order
19 Activate SBC brake system using STAR DIAGNOSIS.
20 Bleed brake system with STAR DIAGNOSIS

CAUTION: The warning buzzer in the instrument cluster is deactivated during the bleeding process. After completing all work, therefore, the STAR DIAGNOSIS menu item "Activate warning buzzer in instrument cluster" must be called to ensure that the warning buzzer functions correctly.

21 Read diagnostic trouble code memory and erase

NOTE: Stored faults must be processed and erased in the fault memories after completing the work. The stored faults can be caused by defective components, assembly as well as lines disconnected during test work and by simulation.