Hydraulic control unit, removing and installing

Special tools, testers and auxiliary items required 

Fig 1: Identifying Torque Wrench V.A.G. 1331

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• Torque wrench V.A.G 1331

Fig 2: Identifying Brake Pedal Depressor V.A.G 1869/2

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• Brake pedal actuator V.A.G 1869/2
• Sealing plugs (repair kit) 1H0 698 311 A 

Removing 

Location:

Fig 3: Locating Hydraulic Unit

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Hydraulic unit is located on left-hand side of engine compartment.

• Note or request radio code on vehicles with coded radio if necessary.
• Disconnect battery →
  • 27 BATTERY, STARTER, GENERATOR, CRUISE CONTROL
  • 27 - BATTERY, STARTER, GENERATOR, CRUISE CONTROL for ELECTRICAL EQUIPMENT - GENERAL INFORMATION

Fig 4: Removing Plenum Chamber Cover

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• Remove plenum chamber cover.

Fig 5: Removing Hex Bolts Securing Coolant Expansion Tank & Disconnecting Connector From Coolant Expansion Tank

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

Fig 6: Moving Coolant Expansion Tank Clear To One Side

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• Move coolant expansion tank clear to one side.

Fig 7: Brake Pedal Depressor VAG 1869/2 Inserted Between Brake Pedal And Driver's Seat

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

• Close left front and left rear bleeder screws.
• Do not remove brake pedal actuator V.A.G 1869/2.
• To protect against escaping brake fluid, place a lint-free rag in the area under the control module and hydraulic unit.

Fig 8: Identifying Brake Lines

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

Fig 9: Identifying Brake Line Retainer

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• Open brake line retainer - 1  -.

Fig 10: Identifying Brake Lines

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• Press red locking slide upward.

• Release control module connector - arrow  - and disconnect.

Fig 11: Pushing Retaining Plate And Disconnecting Connector

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

Fig 12: Removing Hex Bolts

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

Installing 

Installation is in reverse order of removal. Note the following:

Fig 13: Connecting Brake Caliper & Piston Circuit Lines

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• 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.

• 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 VAS 5051 via Guided fault finding function.

• When replacing the control module, select function "Replacing" for the respective control module in the "Guided fault finding".

For this, use vehicle diagnosis, testing and information system VAS 5051. 

• After fastening the brake lines to the hydraulic unit, perform final control diagnosis Vehicle diagnostic, testing and information system. VAS 5051

Tightening torques