Brake System, Bleeding With Empty Brake Fluid Reservoir
Brake System, Bleeding with Empty Brake Fluid Reservoir
Special tools, testers and auxiliary items required
^ Brake Filler and Bleeder Unit VAS 5234
^ Vehicle Diagnostic Testing and Information System VAS 5051 and Cable with 3 m current supply VAS 5051/1
When using a brake system filling and bleeding appliance (such as VAS 5234) to replenish the brake fluid, make sure that filling pressure does not exceed 1 bar.
If the filling pressure exceeds 1 bar, a hydraulically controlled change-over valve (which is required for the EDL function) prevents unrestricted flushing of the EDL-related parts of the hydraulic unit. If this is the case, it may not be possible to bleed the system properly.
For this reason the brake fluid pressure must be reduced to 1 bar on the brake filling and bleeding appliance.
Filler and bleeder unit VAG 1238/B is not suitable for bleeding the brake system by using the "Basic setting" function.
If only filler and bleeder unit VAG 1238/B is available, then switch unit on/off to ensure that sufficient brake fluid is always present in reservoir.
Requirement for test:
^ Connect Vehicle Diagnostic Testing and Information System VAS 5051, select "Vehicle self-diagnosis" and vehicle system "03 Brake electronics".
Pre-Bleeding
- Connect Brake Filler and Bleeder Unit VAS 5234.
- Open bleeder screws in the specified sequence and pre-bleed brake calipers.
1. Bleed left front and right front brake calipers simultaneously.
2. Bleed left rear and right rear brake calipers simultaneously.
- Leave the bleeder screw open, with brake fluid hose connected, until brake fluid free from air bubbles comes out of the bleeder screw.
Bleeding
Display on Vehicle Diagnostic Testing and Information System VAS 5051:
- Select the diagnosis function "04 - Basic settings" from the menu -1-.
Note:
^ During the next steps the ABS warning lamp flashes.
Display on Vehicle Diagnostic Testing and Information System VAS 5051:
1. Enter display group
- Using the keypad -2-, enter "001" to select Display group 001 and confirm entry with Q key.
Display on Vehicle Diagnostic Testing and Information System VAS 5051:
1. System in basic setting
2. Display group 1
3. Press pedal and hold in position.
- Operate pedal with substantial foot pressure and hold.
^ Pedal drops, hydraulic pump starts up, pedal returns
Display on Vehicle Diagnostic Testing and Information System VAS 5051:
3 - Release pedal; FR/FL bleed screws OPEN.
- Release pedal, open front bleeder screws.
- Press the button to advance to Display group 002.
Display on Vehicle Diagnostic Testing and Information System VAS 5051:
1. System in basic setting
2. Display group 2
3. Please wait.. (10 sec.)
- Wait for 10 seconds.
^ Hydraulic pump starts up briefly
Display on Vehicle Diagnostic Testing and Information System VAS 5051:
3 - Press pedal 10X; bleed screws CLOSED>
- Press pedal 10 times, close front bleeder screws.
- Press the button to advance to display group 003.
Display on Vehicle Diagnostic Testing and Information System VAS 5051:
1. System in basic setting
2. Display group 3
3. Press pedal and hold in position.
- Repeat bleeding procedure as specified earlier.
- Press the button several times to advance to the next display groups until display group 17 is indicated.
Display on Vehicle Diagnostic Testing and Information System VAS 5051:
1. System in basic setting
2. Display group 17
3. Partial bleeding over...
- Press the button to exit from diagnosis function "04 - Basic settings".
Display on Vehicle Diagnostic Testing and Information System VAS 5051:
- Select diagnosis function "06 - End output" from the menu -1-.
Display on Vehicle Diagnostic Testing and Information System VAS 5051:
- When this display appears, switch off ignition and unplug diagnostic connector.
- Now perform bleeding of brake system. Brake Bleeding