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Remove |
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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 |
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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 |
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Notes on repairs to brake system |
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AH42.00-P-0003-01A |
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Brake fluid notes |
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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. |
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| 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). |
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| 3 |
Remove right-hand intake air duct |
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| 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).
Replace bolt (17).
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. |
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Bolt, bracket of electrical lines to SBC hydraulic unit |
*BA42.46-P-1005-01B |
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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). |
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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. |
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| 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).
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).
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
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Pliers |
Fig 7 |
| 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.
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.
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. |
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Blade holder with clamping pliers |
Fig 13 |
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MCP 2.8_/Fl. blade 2.8_/JPT/SPT |
Fig 10 |
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Clean |
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| 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
. |
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| Assembly cleaner |
*BR00.45-Z-1028-04A |
| 10 |
Mark hydraulic lines (1) |
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| 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.
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.
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. |
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Union nut, brake line to SBC hydraulic unit |
*BA42.46-P-1001-01B |
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Record plug |
Figure |
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Box wrench bit |
Figure |
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Torque wrench |
Figure |
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Adapter coupling |
Figure |
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Box wrench bit |
Figure |
| 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
. |
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Wedge |
Figure |
| 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
. |
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| 14 |
Remove complete traction system hydraulic unit (A7/3) with retaining plate (8) |
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| 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).
Replace bolt (9). |
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Bolt, hydraulic unit to support plate |
*BA42.46-P-1004-01B |
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Install |
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| 16 |
Install in the reverse order |
Operation steps 14 to 12 |
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| 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. |
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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). |
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| 19 |
Install in the reverse order |
Operation steps 10, 9 and 6 to 3 |
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| 20 |
Use water to rinse off any escaped brake fluid |
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| 21 |
Bleed brake system with STAR DIAGNOSIS |
Bleed brake system with STAR DIAGNOSIS
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. |
AR42.10-P-0012TX |
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Check |
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| 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 leaktightness test. |
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| 23 |
Check fluid level in the expansion reservoir (11) for brake fluid and correct if necessary |
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Brake system - inspect fluid level |
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AP42.10-P-4210TX |
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Cap to brake fluid expansion reservoir |
*BA42.50-P-1001-01D |
| 24 |
Carry out brake test on the test stand |
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Brake test |
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AP42.00-P-4290BA |