Removing and installing control unit and hydraulic unit, LHD vehicles, petrol engines
In this manual: Brake system
~3min read
Special tools and workshop equipment required
Torque wrench -V.A.G 1331-
Torque wrench -V.A.G 1410-
Brake pedal depressor -V.A.G 1869/2-
Sealing plugs, assembly part no. 5Q0 698 311
1 -
Sealing plug M10
2 -
Sealing plug M12
Removing
Location:
The control unit is bolted to the hydraulic unit and is located on right in the engine compartment. Risk of damage to brake lines if bent.Never excessively bend the brake lines in the area of the hydraulic unit.
Read out and note the existing control unit code.
If vehicle has a coded radio, note radio code or, if necessary, request it.
Connect hose of bleed bottle -1- to bleeder valve of front left brake caliper.
Open bleeder valve.
Connect hose of bleed bottle -1- to bleeder valve of rear 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 and rear left bleeder valves.
Do not remove brake pedal depressor -V.A.G 1869/2-.
Note
Ensure no brake fluid gets onto contacts.
Pull cover off plenum chamber bulkhead and unclip brake lines.
First identify both brake lines from brake master cylinder and unscrew from hydraulic unit.
Seal threaded holes immediately using sealing plugs from the assembly part kit with part no. 5Q0 698 311.
Mark, unscrew and seal threaded holes of remaining brake lines (brake calipers).
Pull hydraulic unit together with control unit upwards out of dampers -arrow-.
Installing
Install in reverse order of removal, observing 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. When installing the hydraulic unit, ensure that the rubber dampers are not pressed out of bracket.
Tightening sequence of brake lines:
Remove brake pedal depressor -V.A.G 1869/2-.
Bleed brake system → Chapter.
Code radio.
Code control unit -J104- using → Vehicle diagnostic tester in "Guided Fault Finding".
To do this, carry out basic setting of the steering angle sender -G85-, the lateral acceleration sender -G200-, the longitudinal acceleration sender -G251- and the brake pressure sender -G201-.
Specified torques
→ Chapter „Assembly overview - control unit and hydraulic unit, LHD vehicles“
Battery → Electrical system; Rep. gr.27
Front bleed valves → Chapter „Assembly overview - front brake caliper“
Note
