Skoda Workshop Service and Repair Manuals

Removing and installing the hydraulic control unit and the bracket   Note Make absolutely sure that no brake fluid gets into the plug connector housing of the control unit. This may result in the corrosion of the contacts and to system failure. Carefully clean out the plug connector housing with compressed air if it gets dirty. Special tools and workshop equipment required t  Vehicle system tester -V.A.G 1552- with diagnostic cable -V.A.G 1551/3, 3A, 3B oder 3C- or diagnostic unit VAS t  Brake pedal arrester, e.g. -V.A.G 1238/B- t  Caps from the repair set SP no. -1 HO 698 311 A- t  Brake filling and bleeding device e.g. -VAS 5234- t  Extraction bottle (commercially available) t  Brake fluid → Chapter

1 -	Hydraulic control unit

t	the hydraulic pump -V64-, the hydraulic unit -N55- and the ABS control unit -J104- form the hydraulic control unit.

t	the hydraulic control unit must be removed and installed as a whole unit

t	repairing → Chapter

2 -	Brake line, 14 Nm

t	between the master brake cylinder/floating piston circuit and ABS hydraulic unit

3 -	Brake line, 14 Nm

t	ABS hydraulic unit to front left brake caliper

4 -	Brake line, 14 Nm

t	ABS hydraulic unit to wheel cylinder/rear right brake caliper

5 -	Brake line, 14 Nm

t	ABS hydraulic unit to wheel cylinder/rear left brake caliper

6 -	Brake line, 14 Nm

t	ABS hydraulic unit to front right brake caliper

7 -	Brake line, 14 Nm

t	between master brake cylinder/push rod piston circuit and hydraulic unit

8 -	Multi-pin connector/ABS control unit

t

25-pin

t	do not disconnect the plug connector before the self-diagnosis is complete, switch off the ignition before disconnecting the plug connector

9 -	Self-locking nut, 20 Nm

10 -

Support

11 -	Dowel screw, 8 Nm

12 -	Cap nut, 25 Nm

Remove the hydraulic control unit   Note t  Before disconnecting the battery determine the code of radio sets fitted with anti-theft coding. t  After connecting the battery, perform the following: –  on vehicles with radio encoding, carry out the coding, –  re-set clock, –  initialise power windows on vehicles fitted with power windows → BookletOctavia –  Disconnect battery.   Note The following 2 work steps do not apply to the 1.6 ltr./55 kW engine:

–  Disconnect the plug -1- of the air mass meter from the air guide pipe of the air filter. –  Unscrew screws -2- at the air filter -3- and lay it aside. –  Remove the relay carrier above the brake servo unit on diesel engines. –  Using an extraction bottle extract as much brake fluid as possible from the brake fluid reservoir.

–  Press brake pedal and lock in place with brake pedal load, e.g. -V.A.G 1238/B-. –  Attach the bleeder hose of the bleeding bottle onto the bleeder screw of the front left brake caliper and open the bleeder screw. –  Close the bleeder screw once the brake fluid flowed out. –  Disconnect the bleeder hose from the bleeder screw.

–  Release the multi-pin connector and remove it from the hydraulic unit.   Note Make sure that no brake fluid gets onto the contacts.

–  In order to collect the brake fluid, position an absorption fleece under the hydraulic control unit.   Note The brake lines around the hydraulic unit must not be bent. –  Protect the brake lines from the master brake cylinder to the hydraulic unit against dirt, see -arrows-, with the caps from the repair set SP no. -1 HO 698 311 A-. –  On vehicles with the steering located on the left, tie up the unscrewed brake lines with a welding wire as far to the top until the cable extremities protrude beyond the brake fluid gauge of the expansion reservoir -arrows-. –  Unscrew the remaining brake lines from the hydraulic unit.

–  The connections of the hydraulic lines on the hydraulic unit must be closed with the screw plugs -Pos. 2- and -Pos. 3- from the repair set SP no. -1 HO 698 311 A-. -Pos. 1- Transport protection for valve domes (foam material).

–  Unscrew the screws -arrows- on the bracket for the hydraulic control unit. –  Remove the hydraulic control unit. Install the hydraulic control unit   Note t  Only then remove plugs from the hydraulic unit when the relevant brake line is installed. t  If the plugs were already removed from the hydraulic unit before the brake line is installed, then brake fluid may escape and adequate filling and bleeding can no longer be guaranteed. –  Screw hydraulic control unit onto bracket.   Note Do not tighten screws. This facilitates the screwing of the individual brake lines onto the hydraulic control unit. –  Connect the brake lines to the hydraulic unit and tighten → Chapter.

–  Tighten the hydraulic control unit -arrows-. –  Insert the multi-pin connector on the ABS control unit and lock. Further installation occurs in reverse order. –  Connect battery → Electrical System; Rep. gr.27. –  Bleeding brake system → Chapter. –  Code the control unit → Chapter. –  Interrogate the fault memory → Chapter. –  Erasing fault memory → Chapter. Removing and installing bracket Removing –  Remove the hydraulic control unit → Chapter.

–  Unscrew nuts -1- and cap nut -3-. –  Remove holder -2-. Install Installation is carried out in the reverse order. Tightening torques: Nuts to body: 20 Nm Use new nuts! Cap nut to body: 25 Nm