Removing and installing ABS control unit J104/ABS hydraulic unit N55, Audi A1 quattro — AUDI

🧭 Before you start

Fits: Audi A1 (8X, 2010–2018)

• Opens: coolant, brake fluid, clutch fluid, fuel
• Special tools named: locking bar

Don't miss

• This closes the valves in the brake master cylinder and stops the brake fluid reservoir from running empty.
• Do not remove brake pedal actuatorV.A.G 1869/2.
• Risk of damage to brake linesDo not attempt to bend to a different shape. — First mark the two brake lines (A) and (B) coming from the brake master cylinder.
• Mark brake lines (1) to (4) and unscrew brake lines.
• Make sure brake fluid does not get into connector housing of control unit. This can result in corrosion of the contacts and failure of the system.Use compressed air to carefully clean connector housing if necessary.

📋 Procedure

1. Remove noise insulation General body repairs, exterior66Noise insulation; Exploded view - noise insulation.
2. ⚠ Risk of irreparable damage to electronic components when disconnecting batteryObserve steps required when disconnecting battery. — Disconnect battery Electrical system27Battery; Disconnecting and connecting battery.
3. Remove engine cover panel 10Engine cover panel; Removing and installing engine cover panel.
4. Remove bolt (arrow).
5. Release hose clips (1) and (3) and move air pipe (2) aside with hose connected.

6. Release hose clip (2).
7. Remove intake hose between air pipe and turbocharger.
8. Seal off turbocharger using clean plugs from engine bung setVAS 6122.
9. Detach ACF line (2) from cylinder head cover.
10. Remove bolts (3).
11. Detach crankcase breather pipe with heat shield from cylinder head cover.
12. To do this, release hose clip (1).
13. Press locking slide (2) downwards in direction of (arrow).
14. Release locking bar (1) securing connector (3) on ABS control unit J104.
15. To do this, press locking bar (1) downwards in direction of (arrow).
16. Unplug connector (3) towards front.
17. ⚠ Risk to healthBrake fluid is poisonous and must NOT be drawn off by sucking through a hose.Always wear chemical-resistant protective gloves to prevent brake fluid from contacting skin.Always observe the relevant environmental regulations for disposal.Risk of malfunction if brake fluid comes into contact with fluids containing mineral oils.Do not under any circumstances allow brake fluid to come into contact with fluids that contain mineral oils (e.g. oil, petrol, cleaning agents). Protective gloves must be free of oil and grease.Risk of damage to paintwork surfacesDue to its corrosive effect, brake fluid must not be allowed to come into contact with paintwork. Rinse off brake fluid spillages immediately using plenty of water. — Insert brake pedal actuatorV.A.G 1869/2 between brake pedal and driver's seat. Depress brake pedal by at least 60 mm. [Note: This closes the valves in the brake master cylinder and stops the brake fluid reservoir from running empty.]
18. Attach bleeder hose (1) of bleeder bottle to bleeder screw of front left brake caliper.
19. Open bleeder screw.
20. Attach bleeder hose (1) of bleeder bottle to bleeder screw of rear left brake caliper.
21. Open bleeder screw.
22. Close bleeder screws (front left and rear left).
23. Do not remove brake pedal actuatorV.A.G 1869/2.
24. Place sufficient lint-free cloths under the ABS hydraulic unit N55.
25. Clamp off coolant hoses with hose clamps.
26. Release hose clips (1) and (2) and disconnect coolant hoses from heat exchanger for heater.
27. Remove bolts (2).
28. Detach heat shield (1).
29. Carefully open retainer (2) at retaining tab (arrow).
30. Unclip refrigerant line (1).
31. Disconnect fuel lines (arrows) at connection in engine compartment (right-side).
32. Move fuel lines aside.
33. Release connector (2) and unplug.
34. Unscrew securing bolt (3).
35. Move coolant expansion tank (1) to one side.
36. Remove bolts (arrows) and detach pendulum support.
37. Remove bolts (1) to (4) from engine mounting.
38. Pull engine 3.5 cm forwards in direction of (arrow) at engine mounting.
39. Unclip brake lines (1) at retainers (arrows).
40. ⚠ Risk of damage to brake linesDo not attempt to bend to a different shape. — First mark the two brake lines (A) and (B) coming from the brake master cylinder.
41. Unscrew brake lines from ABS hydraulic unit N55.
42. Mark brake lines (1) to (4) and unscrew brake lines.
43. Seal open connections immediately using clean sealing plugs from repair kit1H0 698 311 A. [Note: Make sure brake fluid does not get into connector housing of control unit. This can result in corrosion of the contacts and failure of the system.Use compressed air to carefully clean connector housing if necessary.]
44. Remove nuts (5) and (6).
45. Detach bracket together with hydraulic control unit.
46. Turn bracket so that nuts are accessible.
47. Loosen three nuts (arrows) securing rubber dampers until rubber dampers can be turned.
48. Unscrew top nut (located at side) as far as shoulder on stud.
49. Lift hydraulic control unit (1) out of bracket in direction of (arrow) and remove. [Note: Fit transport protection after removing hydraulic control unit.No warranty claims for the hydraulic control unit can be accepted if the transport protection is not fitted.] [Note: Do not remove the sealing plugs from the new hydraulic control unit until you are ready to fit the corresponding brake line.If the sealing plugs are removed from the hydraulic control unit too soon, brake fluid may escape and it may not be possible to fill and bleed the unit properly.To facilitate installation, moisten the rubber mountings in the bracket slightly with water.To facilitate installation, first insert all brake lines in the hydraulic unit.Then tighten the brake line connections.]
50. Fit hydraulic control unit (1) in bracket.
51. ⚠ Malfunctions can occur if the unit is not fitted securely.Make sure that the rubber dampers are fitted correctly in the bracket when installing.After installation, check that the ABS hydraulic unit N55 is seated securely, otherwise malfunctions can occur. — Remove sealing plugs from new hydraulic control unit.
52. Insert all brake lines and tighten connections.
53. Clip brake lines (1) into retainers (arrows) on plenum chamber partition panel.
54. Remove brake pedal actuatorV.A.G 1869/2.
55. Bleed brake system .
56. Bleed clutch system 30Clutch mechanism; Bleeding clutch hydraulics.
57. Install engine cover panel 10Engine cover panel; Removing and installing engine cover panel.
58. Connect battery Electrical system27Battery; Disconnecting and connecting battery.
59. Check coolant level 19Cooling system/coolant; Draining and filling cooling system.
60. When renewing ABS control unit J104/ABS hydraulic unit N55, select the "“Replace”" function for the ABS control unit J104/ABS hydraulic unit N55 using , Guided Functions.

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