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

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Install in the reverse order of removal while noting the following:

-- Push the hydraulic control module -1- with the bracket into the pins in the engine compartment -arrows-.

• The hydraulic control module must rest in all pins.
• When installing the hydraulic control module, make sure the rubber buffer is not pushed out of the bracket.
• Only remove the plugs on the new hydraulic unit if the corresponding brake line is installed.
• If the plugs are removed too early from the hydraulic unit, brake fluid can escape and the unit may not be sufficiently filled or adequately bled.

Identification of the hydraulic unit. 

Fig 1: Hydraulic Unit Brake Line Installation Sequence

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A -  Hydraulic Unit To Master Brake Cylinder Primary Piston Circuit -HZ2-

B -  Hydraulic Unit To Master Cylinder Secondary Piston Circuit -HZ1-

1 -  Hydraulic Unit To Right Front Brake Caliper -VR-

2 -  Hydraulic Unit To Left Rear Brake Caliper -HL-

3 -  Hydraulic Unit To Right Rear Brake Caliper -HR-

4 -  Hydraulic Unit To Left Front Brake Caliper -VL-

-- Insert all brake lines into the ABS Hydraulic Unit -N55-, install all union bolts by hand and tighten in the sequence -1 through 6- to the corresponding tightening specification.

Fig 2: Brake Line Tightening Sequence

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Model S3, Gasoline Particulate Filter, Installing: 

Refer to OVERVIEW - EMISSIONS CONTROL SYSTEM .

-- Remove the Brake Pedal Actuator: VAG1869/2  .

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

-- If the ABS Control Module -J104- /ABS Hydraulic Unit -N55- is being replaced, select the "Replace" function for the ABS Control Module -J104- /ABS Hydraulic Unit -N55- on the Vehicle Diagnostic Tester.