ABS Bosch 8.0

ABS Bosch 8.0
The following configurations are possible on vehicles with ABS Bosch 8.0 system:
^ ABS/EDL/ASR/ESP

The ABS brake system is divided diagonally. The brake booster assist is provided pneumatically by the vacuum brake booster unit.

Malfunctions in the ABS system do not influence the brake system and servo. The conventional braking system remains functional even without ABS. A change in braking behavior must be looked at. After the ABS warning lamp comes on, the rear wheels can lock early when braking!

The direct connection between these components reduces possible sources of malfunctions. There is no provision for repairing the hydraulic control unit, it must be replaced if necessary.






Bosch 8.0 ABS/EDL/ASR/ESP:
Removing and installing control module and hydraulic unit

Hydraulic unit and brake lines





1. Brake master cylinder and brake booster
2. Brake line
^ Brake master cylinder/primary piston circuit to hydraulic unit

3. Brake line
^ Brake master cylinder/secondary piston circuit to hydraulic unit

4. Brake line
^ Hydraulic unit to right front brake caliper

5. Brake line
^ Hydraulic unit to left rear brake caliper

6. Brake line
^ Hydraulic unit to right rear brake caliper

7. Brake line
^ Hydraulic unit to left front brake caliper

8. ABS hydraulic unit N55 with ABS control module J104
^ With integrated brake pressure sensor

9. Spacer (2 x)
10. Longitudinal member (body)
11. Combi nut, 10 Nm
12. Bracket for ESP
13. Bolt with bonded rubber bushing, tightening torque 10 Nm
^ Cannot be removed from component

14. Combi nut, 8 Nm
15. Washer

Removing and installing hydraulic control unit
Special tools, testers and auxiliary items required





^ Torque wrench V.A.G 1331
^ Brake pedal actuator V.A.G 1869/2





^ Sealing plugs (repair kit) 1H0 698 311 A

Removing
Location:





The hydraulic control unit is installed on left-hand side of engine compartment.

CAUTION: Brake lines must not be bent.

- Note or request radio code on vehicles with coded radio if necessary.
- Disconnect battery.





- Detach plenum chamber cover.





- Remove hex bolts - 1 - securing coolant expansion tank.
- Disconnect connector from coolant expansion tank.





- Move coolant expansion tank clear to one side.





- Insert brake pedal actuator V.A.G 1869/2 between brake pedal and drivers seat. Depress the brake pedal at least 60 mm.
- Connect bleeder bottle hose to bleeder screw on left front and left rear brake caliper and open bleeder screws.

Note: The pressure in the hydraulic unit is then released.

- Close left front and left rear bleeder screws.
- Do not remove brake pedal actuator V.A.G 1869/2.
- As protection against escaping brake fluid, place a sufficient number of lint-free cloths in area beneath control module and hydraulic unit.

Note: Number brake lines.

CAUTION: The brake lines in the vicinity of the hydraulic unit must not be bent.





- Disconnect brake lines between hydraulic unit and brake master cylinder.
- Disconnect remaining brake lines - arrows - on hydraulic unit.
- Seal brake lines and tapped holes with sealing plugs from repair kit.





- Open brake line retainer - 1 -.
- Press red locking slide upward.





Note:
^ Make sure that the brake fluid does not get into connector housing of control module. This can result in corrosion of the contacts and failure of the system.
^ Use compressed air to carefully clean connector housing if necessary.

- Release control module connector - arrow - and disconnect.





- Push retaining plate in direction of - arrow - and disconnect connector.





- Remove hex bolts -1-.
- Remove hydraulic control unit.

Installing
Installation is performed in reverse sequence; note the following:

Note:
^ Do not remove sealing plugs from new hydraulic unit until corresponding brake line is to be installed.
^ If sealing plugs are removed from hydraulic unit sooner, brake fluid may escape and it may no longer be possible to fill and bleed the unit properly.





Connect lines as previously marked:
1 - To right front brake caliper
2 - To left rear brake caliper
3 - To right rear brake caliper
4 - To left front brake caliper
5 - To primary piston circuit
6 - To secondary piston circuit

- Install connector on hydraulic pump.
- Clip ABS unit onto bracket.

Note: Do not tighten bolts completely. This will make attaching the individual brake lines easier.

- After tightening brake lines, tighten hydraulic unit.
- Remove brake pedal depressor V.A.G 1869/2.
- Bleed brake system Brake system, bleeding.
- Code ABS control module J104. Code control unit using VAS5051 via Guided fault finding function.
- When replacing the control module, select function Replacing for the relevant control module in the Guided fault finding.

To do so, use the vehicle diagnosis, testing and information system VAS 5051A.
- Perform final control diagnosis after attaching brake lines to hydraulic unit. Vehicle diagnostic, testing and information system. VAS 5051A

Note: Final control diagnosis can be used to establish whether line connections have been interchanged ABS system components on front axle, removing and installing.

Tightening torques