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

MODEL 219 with Sensotronic Brake Control (SBC) 

Fig 1: Identifying Brake Operating Unit (BOU) Remove/Install 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.
	Connect STAR DIAGNOSIS and read out fault memory		AD00.00-P-2000-04A
		STAR DIAGNOSIS, diagnosis system	*WH58.30-Z-1048-13A
2	Take off cover (1)
3	Disconnect electrical connector to the brake fluid indicator switch (S11)
4	Suction off brake fluid from the expansion reservoir (2)	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)	Clean the area around the separation point 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 SBC feed line (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-1002-02B
8	Pull the expansion reservoir (2) out of the brake operating unit (BOU) (5)	Check seals (6) for damage; replace if necessary. 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)	Collect brake fluid which flows out with a non-fluffing, absorbent cloth. Seal connections immediately.
			*BA42.46-P-1003-02B
			*BA42.46-P-1004-02B
			Fig 2
			Figure
11	Remove left cover below instrument panel		AR68.10-P-1500TX
12	Remove stop lamp switch (S9/1)		AR42.10-P-0040TX
13	Remove clutch pedal switch (S40/3)	Press the locking catch and turn the 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-1001-02B
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-0012TX

BRAKE OPERATING UNIT (BOU)

Number	Designation		Model 219
BA42.46-P-1001-02B	Nut, BOU to firewall	Nm	20
BA42.46-P-1002-02B	Bolt expansion reservoir to brake operating unit (BOU)	Nm	5
BA42.46-P-1003-02B	Pressure connection, primary circuit	Nm	13
BA42.46-P-1004-02B	Pressure connection, secondary circuit	Nm	13

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 diagnosis system, Compact Passenger Car	6511 1801 00