Audi Workshop Service and Repair Manuals > A4 Cabriolet Mk2 > Brake system | ABS, ADR, TCS, EDL, ESP | Anti-lock brake system (ABS) Bosch 5.7

Renewing ABS control unit J104

Removing

Caution

The two components must be removed from the vehicle before separating the control unit from the hydraulic unit. → Chapter

Note

t	Clean the hydraulic unit carefully before removal.

t	Before removing the control unit, interrogate the fault memory and print out any fault codes that are displayed.

t	Place the hydraulic unit together with the control unit on a clean flat surface.

t	Renewal may only be performed by qualified personnel with adequate technical expertise.

Removing and installing hydraulic unit → Chapter

–	Slacken bolts -1- and pull control unit -2- off hydraulic unit, taking care to keep it straight.

–	Clean sealing surface -2- using a plastic scraper -1-. Check valves -3- for damage.

WARNING

Sealing surface of hydraulic unit must be clean and flat.

The hydraulic unit must be renewed if the sealing surface or the contact pins are damaged.

The seal on the control unit cannot be replaced.

The seal on the control unit must not be lifted or pulled out.

Note

t	Use the cleaning agent provided (do not use any aggressive cleaning products).

t	Check sealing surface for damage (visual inspection).

Assembling

Caution

Make sure that no moisture or dirt gets inside the control unit.

Do not blow out control unit or hydraulic unit with compressed air.

Severe shocks or jolts can damage the control unit. The control unit must not be re-installed if it has been damaged in any way.

–	With solenoids pointing downwards, carefully press on control unit -1-, guiding it over valves on hydraulic unit -2-. Make sure that valves remain straight.

–	The edge of the control unit housing must slide over the shoulder on the hydraulic unit.

Note

t	Use new bolts.

t	To avoid any risk of leakage at the flexible seals, a new control unit must not be fitted more than twice onto an "old" hydraulic unit that is being re-installed.

t	A control unit which has been in operation while the vehicle is being driven must not be fitted a second time.

–	Push control unit onto ABS hydraulic unit (N55) and screw in new bolts -1- and -2- evenly (without tightening) until control unit makes even contact with hydraulic unit.

–	Screw in bolts -1- to -6- all the way, but do not tighten.

–	Tighten bolts -1- to -6- in the sequence shown.

Tightening torque: 2.9 Nm.

–	After tightening, check that all bolt heads are seated flush.

–	Install assembled unit → Chapter.

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