Remove/install Sensotronic Brake Control (SBC) hydraulic unit

AR42.46-P-0010TX

Remove/install Sensotronic Brake Control (SBC) hydraulic unit

06.03.2020

Model

219

with Sensotronic Brake Control (SBC)

Modification notes

05.08.2010

"Perform brake test on test bench" reference changed

Test sequence augmented/revised

1

Hydraulic line

2a

Suction hose

3

Return flow pipe

8

Retaining plate

9

Screw

A7/3

Traction system hydraulic unit

15d

Bracket

15s

Bracket

16

Pressure reservoir

17

Screw

A7/3

Traction system hydraulic unit

Line diagram

2

Suction pipe

VB

Suction hose connecting point (2b) to suction line (2)

2a

Suction hose

VC

Suction hose connecting point (2a) to suction line (2)

2b

Suction hose

VD

Intake hose connection (2a) to traction system hydraulic unit (A7/3)

11

Expansion reservoir

A7/3

Traction system hydraulic unit

VA

Suction hose connecting point (2b) to expansion reservoir (11)

A7/3n1

SBC control unit



Remove

 Warning

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

 Caution

Risk of poisoning from swallowing brake fluid. Risk of injury from skin and eye contact with brake fluid

Only pour brake fluid into suitable and appropriately marked containers. Wear protective clothing and eye protection when handling brake fluid.

AS42.50-Z-0001-01A

Topical note

Notes on repairs to brake system

AH42.00-P-0003-01A

Topical note

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 Operation steps from top to bottom.

2

Switch ignition off, remove ignition key (transmitter key)

 On vehicles with code 889 Keyless-Go: Press Keyless-Go start/stop button repeatedly until the ignition is switched off.
Remove Keyless Go transmitter card or transmitter key from the vehicle and store beyond transmitter range (min. 2 m).

3

Remove right-hand intake air duct

4

Remove bolt (17) and remove bracket (15s) with electrical SBC wiring harness


Cut cable strap on electrical SBC wiring harness only when replacing bracket (15s).
This is because of the risk of damage involved.

 When replacing the traction system hydraulic unit (A7/3), mount old bracket (15s) to new traction system hydraulic unit (A7/3), as a new traction system hydraulic unit (A7/3) is supplied without a bracket (15s).

 Installation: Replace screw (17).

 Installation: If the thread for bolt (17) in the traction system hydraulic unit (A7/3) is damaged, the bracket (15d) that is to be attached to the pressure reservoir (16) must be used.

 Bolt, bracket of electrical lines to SBC hydraulic unit

*BA42.46-P-1005-01B

 Hose clamp for bracket of electrical lines to SBC pressure reservoir

*BA42.46-P-1006-01B

5

Detach bracket (15d) with electrical SBC wiring harness from pressure reservoir (16)


Cut cable strap on electrical SBC wiring harness only when replacing bracket (15d).
This is because of the risk of damage involved.

 When installing a new traction system hydraulic unit (A7/3), attach the old bracket (15d) to the new pressure reservoir (16) as a new traction system hydraulic unit (A7/3) is supplied without a bracket (15d).

 Hose clamp for bracket of electrical lines to SBC pressure reservoir

*BA42.46-P-1006-01B

6

Release and detach connector of electrical SBC wiring harness on SBC control unit (A7/3n1)

 Place connector in a safe place.

7

Detach electrical SBC wiring harness from bracket (15d, 15s) by cutting through cable strap


Exercise extreme caution when cutting the cable strap.
To ensure that the electrical SBC wiring harness is not damaged!

 Only when replacing the ground wiring harness in the course of replacing the traction system hydraulic unit (A7/3) or when replacing the bracket (15d, 15s).

 Installation: When attaching the electrical SBC wiring harness to the bracket (15d, 15s), always ensure that the electrical SBC wiring harness contacts the bracket (15d, 15s) and is secured there free of tension.
After the electrical SBC wiring harness has been secured, it should no longer be possible to push it in a longitudinal direction toward the bracket (15d, 15s).

 Installation: Always secure the electrical SBC wiring harness to the bracket (15d, 15s) free of tension using cable tie pliers and with a tightening force of 150 N to 170 N. Observe the various settings on the cable tie pliers for the specified tightening force:
 Panduit cable tie pliers: Setting HVY 5
 Hellermann cable tie pliers: Setting STD 3

 Pliers

*352589023700

8

Replace ground wiring harness of electrical SBC wiring harness


To remove the ground line plug contact from the connector housing solely using blade holder with clamping pliers and blade MCP 2.8/ Fl. 2,8/ JPT/ SPT.
Otherwise damage may occur to the connector housing, which would then make it necessary to replace the complete electrical SBC wiring harness!

 Only when replacing the traction system hydraulic unit (A7/3).

 Open connector housing of electrical SBC wiring harness and secondary lock of contact strip. Press ground line plug contact out of pin 37 and pin 44 using blade holder with clamping pliers and blade MCP 2.8/ Fl. 2.8/ JPT/ SPT. Remove ground lines.

 Installation: Make sure that the longer ground line of the ground line wiring harness is inserted into pin 44 and the shorter ground line into pin 37 of the connector housing.

 Installation: Make sure that there is no contact between the ground point of the vehicle longitudinal member and any water hose or other lines.

 Only the ground line of the electrical SBC wiring harness should be connected to the ground point of the vehicle longitudinal member,
otherwise the SBC system could malfunction.

 Blade holder with clamping pliers

*220589019950

 MCP 2.8_/ Fl. blade 2.8_/ JPT / SPT

*000589139930



Clean

9

The traction system hydraulic unit (A7/3) and area around the connecting points should be cleaned thoroughly before the SBC system is opened


Thoroughly clean area surrounding connections.
Even the smallest particles of dirt, introduced into the hydraulic components, can lead to malfunctions of the SBC system.

Assembly cleaner

*BR00.45-Z-1028-04A

10

Mark hydraulic lines (1)

11

Detach hydraulic lines (1) from the SBC hydraulic unit (A7/3)


Seal all hydraulic lines (1) and connections on the traction system hydraulic unit (A7/3) immediately with stop plugs to prevent any air from escaping.
Air in the SBC system reduces braking power and can lead to malfunctions in the SBC system.

 When replacing the traction system hydraulic unit (A7/3) use stop plugs from the new traction system hydraulic unit (A7/3), to seal the old traction system hydraulic unit (A7/3).
129 589 00 91 06 (7 ea.)
129 589 00 91 05 (1 ea.)

 When reusing the traction system hydraulic unit (A7/3) note ordering instructions for stop plugs.

 Installation: Observe markings to avoid swapping the hydraulic lines (1)! When routing the hydraulic lines (1), take extra care to ensure that the hydraulic lines (1) are not resting against other components, that they are not under tension and that they are not twisted. When tightening the hydraulic lines (1), always observe the torque value and make sure that the hydraulic lines (1) are not twisted.

 Installation: The operating noise of the SBC system will be louder if the hydraulic lines (1) rest against other components, are under stress or are twisted.

 Union nut, brake line to SBC hydraulic unit

*BA42.46-P-1001-01B

 Record plug

*129589009100

 Box wrench bit

*000589750300

 Torque wrench

*001589872100

 Adapter coupling

*001589001600

 Box wrench bit

*140589000300

12

Detach suction hose (2a) from SBC hydraulic unit (A7/3)


Seal intake hose (2a) and connection on traction system hydraulic unit (A7/3) immediately with stop plugs to prevent any air from escaping.
Air in the SBC system reduces braking power and can lead to malfunctions in the SBC system.

 Wedge

*601589076300

13

Detach return line (3) from traction system hydraulic unit (A7/3)


Seal return line (3) and connection on traction system hydraulic unit (A7/3) immediately with stop plugs to prevent any air from escaping.
Air in the SBC system reduces braking power and can lead to malfunctions in the SBC system.

14

Remove complete traction system hydraulic unit (A7/3) with retaining plate (8)

15

Remove bolt (9) and remove retaining plate (8) from removed traction system hydraulic unit (A7/3)

 When installing a new traction system hydraulic unit (A7/3).

 Mount old retaining plate (8) to new traction system hydraulic unit (A7/3) because a new traction system hydraulic unit (A7/3) is supplied without a retaining plate (8).

 Installation: Replace screw (9).

 Bolt, hydraulic unit to support plate

*BA42.46-P-1004-01B



Install

16

Install in the reverse order

Operation steps 14 to 12

17

Remove stop plugs and attach return line (3) to traction system hydraulic unit (A7/3)

 When routing the return line (3), take extra care to ensure that it does not rest against other components and is not installed under stress. When tightening the return line (3) the given torque value must be used and ensure that the return line (3) is not twisted.

 The operating noise of the SBC system will be louder if the return line (3) rests against other components, is under stress or is twisted.

 Union nut, return line to SBC hydraulic unit

*BA42.46-P-1002-01B

18

Replace suction hose (2a)


Do not use a screwdriver or a pointed, sharp-edged tool to press off the intake hose (2a).
Otherwise the suction line (2) will be damaged and air may enter the line. Immediately seal suction line (2) with stop plugs to prevent air from entering. Air in the SBC system reduces braking power and can lead to malfunctions in the SBC system.

 Only intake hose with 15.5 mm outside diameter (old version).

 Intake hose with 14 mm outside diameter (new version), only replace if damaged.

 Observe different variants of intake hose (2a).

 If a pulsation damper was not fitted in the intake hose (2a) , install new intake hose (2a) without pulsation damper.

 If a pulsation damper was fitted in the intake hose (2a), install new intake hose (2a) with pulsation damper.

 Mount new suction hose (2a) on suction line (2) losing as little brake fluid as possible. Fill suction hose (2a) with brake fluid before mounting to traction system hydraulic unit (A7/3).

 Hold suction hose (2a) as vertical as possible and fill with brake fluid using a small funnel or syringe. The funnel or syringe must be absolutely clean and must not previously have come into contact with mineral oil (engine oil etc.).

 Push intake hose (2a) without losing any brake fluid loss onto intake connection of traction system hydraulic unit (A7/3). The intake hose (2a) must be routed unstressed and must not contact the hydraulic lines (1) or return line (3).

19

Install in the reverse order

Operation steps 10, 9 and 6 to 3

20

Use water to rinse off any escaped brake fluid

21

Bleed brake system with STAR DIAGNOSIS

Bleed brake system with STAR DIAGNOSIS

AR42.10-P-0012TX

 When performing the bleeding operation always 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 "Initial startup after repair" / "Exchanging the hydraulic unit".
Then process all the individual Operation steps from top to bottom.



Check

22

Check connecting points of hydraulic lines (1), suction hoses (2a, 2b) and return line (3) for leaks


In particular, the connecting points (VA, VB, VC, VD) of the suction hoses (2a, 2b) must be checked very carefully (tissue paper or similar).
 VA: Suction hose connecting point (2b) to expansion reservoir (11).
 VB: Suction hose connecting point (2b) to suction line (2).
 VC: Suction hose connecting point (2a) to suction line (2).
 VD: Intake hose connection (2a) to traction system hydraulic unit (A7/3).
Visual inspection is not enough as even minimal leakage which is not detectable at first glance can lead to malfunctions of the SBC system.

 Connect filling unit and allow the maximum filling pressure of the filling unit (2.5 to 3.0 bar) to be applied statically for 10 minutes. Then check the connecting points of the hydraulic lines (1), suction hoses (2a, 2b) and return line (3) for leaks.
Even the smallest drops of brake fluid are a sign of leakage!

 Finish "SBC" diagnosis after leak tightness test.

23

Check fluid level in the expansion reservoir (11) for brake fluid and correct if necessary



Brake system - inspect fluid level

AP42.10-P-4210TX

 Cap to brake fluid expansion reservoir

*BA42.50-P-1001-01D

24

Carry out brake test on the test stand



Brake test

AP42.00-P-4290BA

 Sensotronic Brake Control (SBC)

Number

Designation

Model 219

BA42.46-P-1001-01B

Union nut, brake line to SBC hydraulic unit

Nm

16

 Sensotronic Brake Control (SBC)

Number

Designation

Model 219

BA42.46-P-1002-01B

Union nut, return line to SBC hydraulic unit

Nm

16

 Sensotronic Brake Control (SBC)

Number

Designation

Model 219

BA42.46-P-1004-01B

Bolt, hydraulic unit to support plate

Nm

30

 Sensotronic Brake Control (SBC)

Number

Designation

Model 219

BA42.46-P-1005-01B

Bolt, bracket of electrical lines to SBC hydraulic unit

Nm

7

 Sensotronic Brake Control (SBC)

Number

Designation

Model 219

BA42.46-P-1006-01B

Hose clamp for bracket of electrical lines to SBC pressure reservoir

Nm

5

 Brake system - hydraulics

Number

Designation

Model 219

BA42.50-P-1001-01D

Cap to brake fluid expansion reservoir

Nm

2

Repair materials

Number

Designation

Order number

BR00.45-Z-1028-04A

Assembly cleaner

A 000 986 56 01