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Home >> Audi >> 2021 >> A4 Quattro Premium Plus, 2.0L Eng VIN B >> Repair and Diagnosis >> Brakes >> Anti-Lock Brakes >> Antilock Brake System (2 Of 2) >> 45 Antilock Brake System >> Control Module And Hydraulic Unit >> ABS Control Module -J104- /ABS Hydraulic Unit -N55-, REMOVING AND INSTALLING >> Removing

ABS Control Module -J104- /ABS Hydraulic Unit -N55-, REMOVING AND INSTALLING: Removing

Fig 1: Brake Pedal Depressor VAG 1869/2 Inserted Between Brake Pedal And Driver's Seat
GWWA44-0020Courtesy of AUDI OF AMERICA, LLC

-- Insert the :VAG1869/2  between the brake pedal and driver seat. Press the brake pedal down at least 60 mm.

TIP:

By doing this, the valves in the brake master cylinder are closed and the brake fluid reservoir does not run empty.

CAUTION:

Leaking brake fluid increases the risk of injury.

Risk of skin irritation and injury.

- Wear safety gloves.

-- Remove the protective cap -3- from the bleed screw -1- on a front brake caliper.

Fig 2: Identifying Protective Cap, Bleed Screw And Container Bleeder Hose
GWWA46-10203Courtesy of AUDI OF AMERICA, LLC

-- Connect the bleeder bottle hose -2-.

-- Open the bleed screw to reduce the pressure in the brake system.

-- Close the bleed screw and remove the bleeder bottle.

-- Repeat the procedure on a rear brake caliper.

-- Remove the engine/motor control module. Refer to ENGINE CONTROL MODULE -J623-, REMOVING AND INSTALLING .

-- If necessary, free up the coolant line -3- and the wiring harness -2-.

GWWA15-11893Courtesy of AUDI OF AMERICA, LLC

-- Depending on the model, remove two or three bolts -arrows- and remove the engine/motor control module mount.

-- To protect against escaping brake fluid, place enough lint-free cloths in the area below the hydraulic control unit.

-- Mark the brake lines for reinstallation.

-- Remove the brake lines -1 and 2- from the ABS Hydraulic Unit -N55-.

GWWA45-10349Courtesy of AUDI OF AMERICA, LLC
CAUTION:

Risk of destroying the brake lines by bending.

- Never change the shape of the brake lines.

-- Seal the brake lines and threaded holes immediately with clean plugs from the Engine Bung Set :VAS6122  .

-- Carefully remove the ABS Control Module -J104- with the ABS Hydraulic Unit -N55- -1- from the pins -arrows-.

GWWA45-10354Courtesy of AUDI OF AMERICA, LLC

-- Only take the hydraulic control unit far enough out of the vehicle in order to disconnect the connector.

-- Release the connector for the ABS Control Module -J104- -3- and disconnect it from the control module.

GWWA45-10349Courtesy of AUDI OF AMERICA, LLC

TIP:

Make sure that no brake fluid enters the control module connector housing.

-- Remove the ABS Control Module -J104- with the ABS Hydraulic Unit -N55- from the vehicle.

-- Turn the ABS Control Module -J104- with the ABS Hydraulic Unit -N55-

-- Seal the brake lines and threaded holes immediately with clean plugs from the Engine Bung Set :VAS6122  .

-- If necessary, remove the bolt -arrow- and remove the bracket -1-.

GWWA45-10251Courtesy of AUDI OF AMERICA, LLC