Removing and installing ABS control unit J104/ABS hydraulic unit N55, MK25 — VW

Removing and installing
ABS control unit
J104
/
ABS hydraulic unit
N55
, MK25
Special tools and workshop equipment required
Torque wrench
V.A.G 1331
Open ring spanner insert, AF 11 mm
V.A.G 1410/6
Universal joint
V.A.G 1410/7
Torque wrench
VAS 6854
Brake pedal depressor
V.A.G 1869/2
Assembly tool
V.A.G 1410/8
Location:
The control unit is bolted to the hydraulic unit and is located on left in the engine compartment.
WARNING
Do not bend the brake lines in the area of the hydraulic unit!
Removing
Note or request radio code on vehicles with coded radio if necessary.
Disconnect battery
Electrical system
Rep. gr.
27
Battery; Disconnecting and reconnecting battery
.
Remove bolt
arrow
.
Remove trim
1
on left next to battery.
Unbolt cooling system expansion tank and lay to side without opening cooling system.
Detach lines
1
from fuel filter
2
.
Loosen clamp
3
.
Lay fuel filter to one side.
Release control unit connector in direction of
arrow
, and pull it off.
Apply
brake pedal depressor
V.A.G 1869/2
.
Connect bleeder hose of bleeder bottle to bleeder valve of front left brake caliper.
Open bleeder valve.
Depress brake pedal at least 60 mm using
brake pedal depressor
V.A.G 1869/2
.
Close front left bleeder valve.
Do not remove
brake pedal depressor
V.A.G 1869/2
.
Place sufficient lint-free cloths under the control unit and hydraulic unit.
Note
Ensure no brake fluid gets onto contacts.
Disconnect brake lines
1
from hydraulic unit.
Seal brake lines and threaded holes using
sealing plugs
1H0 698 311 A
.
Unscrew bolt
arrow
from bracket for control unit/hydraulic unit.
Unscrew bolts
arrows
from bracket for control unit/hydraulic unit.
Remove hydraulic unit together with control unit.
Installing
Installation is performed in reverse sequence; note the following:
Note
Remove sealing plugs from new hydraulic unit only when the corresponding brake line is to be fitted.
If sealing plugs are removed too early from the hydraulic unit, brake fluid can escape, and it can then no longer be guaranteed that the unit can be sufficiently filled and bled.
Order of brake line on hydraulic unit
Chapter
.
After tightening brake lines, tighten hydraulic unit.
Remove
brake pedal depressor
V.A.G 1869/2
.
Bleed brake system
Chapter
.
Code radio.
Coding
ABS control unit
J104
:
Vehicle diagnostic tester
.
Specified torques
Chapter
“
Assembly overview -
ABS control unit
J104
/
ABS hydraulic unit
N55
, MK25
”