Bleeding brake system if brake fluid reservoir has run empty — AUDI

Special tools and workshop equipment required

Brake filling and bleeding appliance VAS 5234

Or

Brake filling and bleeding appliance V.A.G 1869 A

Vehicle diagnostic, testing and information system VAS 5051 with VAS 5051/1

Basic setting is only necessary on vehicles with ABS/EDL.

When using filling and bleeding appliance, e.g. VAS 5234 or V.A.G 1869 A, to replenish brake fluid care must be taken to ensure that filling pressure does not exceed 1 bar.

In the event of a filling pressure greater than 1 bar, a hydraulically actuated switching valve for the EDL control system prevents full flushing of the areas of the hydraulic unit specific to EDL. Proper bleeding is then no longer guaranteed.

The brake fluid pressure at the filling and bleeding appliance must therefore be reduced to 1 bar.

=> VAS 5234 or V.A.G 1869 A operating instructions

The filling and bleeding appliance V.A.G 1238/B is not suitable for bleeding the brake system using the "Starting basic setting" function.

If this is the only equipment available, the filling and bleeding appliance V.A.G 1238/B must be switched on and off as appropriate to ensure that there is always sufficient brake fluid in the reservoir.

Requirement:

Vehicle diagnostic, testing and information system VAS 5051 connected up; vehicle self-diagnosis and vehicle system "03 - Brake electronics" selected

=> Running Gear, Self-diagnosis; Repair Group 01
Running Gear, Self-diagnosis

Pre-bleeding

Connect up brake filling and bleeding appliance VAS 5234 or V.A.G 1869 A.
Open bleed screws in prescribed sequence and pre-bleed brake calipers.

1 -
Simultaneously bleed both front left and front right brake caliper
2 -
Simultaneously bleed both rear left and rear right brake caliper

With bleeder bottle hoses attached, leave bleed screws open until the brake fluid which emerges is free from bubbles.

Bleeding

Display on VAS 5051:

From list -1- select diagnosis function "04 - Basic setting".

Note:

ABS warning lamp flashes in the course of the following operations.

Display on VAS 5051:

1 -
Enter display group

Use keypad -2- to enter "001" for "Display group number 001" and confirm by touching Q key.

Display on VAS 5051:

1 -
Basic setting
2 -
Display group 1
3 -
Press and hold pedal ...

Press pedal firmly and hold in position.
Pedal sags, hydraulic pump starts up briefly, pedal returns

Display on VAS 5051:

3 -
Release pedal; FR/FL bleed screws OPEN <>

Release pedal, open front bleed screws.

Touch s key to switch to display group 002.

Display on VAS 5051:

1 -
Basic setting
2 -
Display group 2
3 -
Please wait .. (10 sec.)

Wait 10 seconds.
Hydraulic pump starts up briefly

Display on VAS 5051:

3 -
Press pedal 10X; bleed screws CLOSED <>

Press pedal 10 times, close front bleed screws.

Touch s key to switch to display group 003.

Display on VAS 5051:

1 -
Basic setting
2 -
Display group 3
3 -
Press and hold pedal ...

Repeat bleeding procedure as described above.
Touch s key in each case to switch to next highest display group until display group 17 is reached.

Display on VAS 5051:

1 -
Basic setting
2 -
Display group 17
3 -
Partial bleeding over ...

Terminate function "04 - Basic setting" by touching ◂ key.

Display on VAS 5051:

From list -1- select diagnosis function "06 - End of output".

Display on VAS 5051:

Switch off ignition and unplug diagnostic connector when this display appears.
Brake system must then be bled => Page
47-19
.

Special feature of right-hand drive vehicles:

If one chamber of brake fluid reservoir is completely empty, brake master cylinder must be bled at bleed screws -arrows- on completion of basic setting.