Remove/install brake operating unit (BOU) - AR42.46-P-0020R

MODEL 230 

Fig 1: Identifying Brake Operating Unit (BOU) Components

Courtesy of MERCEDES-BENZ USA

	Remove/install
	Risk of injury  caused by body parts being jammed or crushed. Risk of injury  to skin and eyes caused by brake fluid spraying out at high pressure when working on the SBC brake system	Deactivate SBC brake system using STAR DIAGNOSIS.	AS42.46-Z-0001-01A
	Risk of poisoning  caused by swallowing brake fluid. Risk of injury  caused by 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.	AS42.50-Z-0001-01A
	Notes on repairs to brake system		AH42.00-P-0003-01A
	Brake fluid notes		AH42.50-P-0001-01A
1	Deactivate SBC brake system using STAR DIAGNOSIS.	The following steps should be run through in STAR DIAGNOSIS: Select menu item "SBC-Sensotronic Brake Control"/"Deactivate 'SBC' system". Then process all the individual steps from top to bottom.
		STAR DIAGNOSIS diagnostic system	*WH58.30-Z-1048-13A
2	Take off cover (1)	Model 211
3	Disconnect electrical connector to the brake fluid indicator switch (S11)
4	Suction off brake fluid from the expansion reservoir (2)	Installation:  Check that the expansion reservoir (2) is seated correctly. No brake fluid may escape from the seals (6), otherwise the SBC system can malfunction.
5	Detach return line SBC (3) from expansion reservoir (2)	The area around the separation point should be cleaned thoroughly before opening the SBC system. Even minute particles of dirt, introduced into the hydraulic components, can result in malfunctions and a total failure of the SBC system.
6	Detach feed line SBC (4) from expansion reservoir (2)	Collect escaping brake fluid using a lint free, absorbent rag and immediately seal connections using stop plugs.
			Figure
7	Unscrew bolt (2a)		*BA42.46-P-1002-02A
8	Pull the expansion reservoir (2) out of the brake operating unit (BOU) (5)	Check seals (6) for damage; replace if necessary. Installation:  The gaskets (6) have no collar and, when assembling the expansion reservoir (2), can be pressed out of the brake operating unit (BOU) (5). Therefore, mount the expansion reservoir (2) vertically on the brake operating unit (BOU) (5) and simultaneously press into the front and rear seal (6).
9	Disconnect electrical connector on SBC pedal value sensor (B37/1)
10	Detach the brake lines (7) from the Brake Operating Unit BOU (5)	Clean up escaped brake fluid using non-fluffy, absorbent cloth and seal connections using blind plugs.
			*BA42.46-P-1003-02A
			*BA42.46-P-1004-02A
			Fig 2
			Figure
11	Remove left cover below instrument panel	Model 211	AR68.10-P-1500T
		Model 230	AR68.10-P-1500R
12	Remove stop lamp switch (S9/1)	Model 211	AR42.10-P-0040I
13	Remove clutch pedal switch (S40/3)	Model 211 Press the locking catch and turn clutch pedal switch (S40/3) clockwise through 90°.
14	Unclip cover (8) on brake pedal
15	Remove stud (9) from brake pedal
16	Unscrew nut (5a) from brake operating unit (BOU) (5)		*BA42.46-P-1001-02A
17	Remove brake operating unit (BOU) (5)
18	Install in the reverse order
19	Bleed brake system with STAR DIAGNOSIS	When performing the bleeding operation, it is essential to observe the instructions in the document "Bleeding brake system using STAR DIAGNOSIS". The following steps should be run through in STAR DIAGNOSIS: Select menu item "commissioning after repair"/"exchange of brake operating unit (BOU)". Then process all the individual steps from top to bottom.	AR42.10-P-0012R

BRAKE OPERATING UNIT (BOU)

Number	Designation		Model 230
BA42.46-P-1001-02A	Nut, BOU to firewall	Nm	20
BA42.46-P-1002-02A	Bolt, BOU expansion reservoir	Nm	5
BA42.46-P-1003-02A	Pressure connection, primary circuit	Nm	16
BA42.46-P-1004-02A	Pressure connection, secondary circuit	Nm	16

Fig 2: Identifying Box Wrench Bit (000 589 77 03 00)

Courtesy of MERCEDES-BENZ USA

Fig 3: Identifying Set Of Stop Plugs (129 589 00 91 00)

Courtesy of MERCEDES-BENZ USA

COMMERCIALLY AVAILABLE TOOLS

Number	Designation
WH58.30-Z-1048-13A	STAR DIAGNOSIS diagnostic system, Compact Passenger Car	6511 1801 00