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

2025 Audi A4 Quattro PrestigeSECTION Installing
Fig 1: Hand Tightening Union Bolts
GWWA45-10349Courtesy of AUDI OF AMERICA, LLC

Install in reverse order of removal while noting the following:

-- If necessary, install the hydraulic control unit bracket.

-- Insert the hydraulic control unit just far enough into the vehicle in order to connect the connector -3-.

-- Carefully push the hydraulic control unit -1- into the pins -arrows-.

Fig 2: Identifying ABS Control Module with ABS Hydraulic Unit Removal
GWWA45-10354Courtesy of AUDI OF AMERICA, LLC
  • The hydraulic control module must rest in all pins.

-- Remove the plug.

-- Insert the brake lines -1 and 2- into the ABS Hydraulic Unit -N55- and then install the union bolts by hand and tighten.

Fig 3: Hand Tightening Union Bolts
GWWA45-10349Courtesy of AUDI OF AMERICA, LLC

-- After securing the brake lines to the hydraulic unit select the "Hydraulic connections, basic setting" program. Refer to DIAGNOSTIC ENTRIES .

-- Remove the Brake Pedal Actuator:V.A.G 1869/2  .

-- Remove all cloths from the vehicle that were previously placed down.

-- Bleed the brake system. Refer to HYDRAULIC SYSTEM, BLEEDING .

-- Complete the "Control module, replacing" program after replacing the hydraulic control unit using the Vehicle diagnostic tester .

CAUTION:

Faulty brakes increase the risk of an accident.

- Make sure the brakes are working correctly before driving the vehicle for the first time.

RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.