Electronic Brake Control Module: Service and Repair

Hydraulic Unit/ABS Control Module, Removing And Installing





Required Special Tools And Equipment
^ VAG 1331 Torque wrench or equivalent
^ VAG 1410 Torque wrench or equivalent
^ VAG 1869/2 Brake pedal depressor or equivalent

Additional Required Information Sources
^ ABS, ABS/EDL On Board Diagnostic (OBD) Refer to Powertrain Management; Computers and Control Systems.

Component Location:
The ABS control module is bolted together with the hydraulic unit and is located in the engine compartment, left side.

Caution!
^ Brake lines in the area of the hydraulic unit should not be bent!

Removing
- For vehicles with a coded radio, obtain code.
- Disconnect battery.





- Disconnector connector -1- of Mass Air Flow MAF sensor from air filter tube
- Remove bolts -2- at air filter -3- and move filter to left side.
- On vehicles with Diesel engines, remove relay panel above brake booster.
- Remove as much brake fluid as possible from brake fluid reservoir using a brake bleeder bottle.
- Insert brake pedal depressor VAG 1869/2 or equivalent.
- Activate brake pedal booster with brake pedal depressor.
- Connect bleeder bottle hose to bleed screw of left front brake caliper and open bleed screw.
- Close left front bleed screw.





- Release ABS control module connector (arrow -1-) and remove (arrow -2-).
- Place plastic covering under control module and hydraulic unit. Do not use rags.

Note:
Do not let brake fluid enter electrical connectors.





- Disconnect brake lines from hydraulic unit to brake master cylinder (arrows) and suspend with wire.
- Disconnect remaining brake lines from hydraulic unit.
- Seal brake lines and threaded holes (arrows) using plugs from repair kit, Part No. 1 H0 698 311 A.





- Remove bolts from bracket for hydraulic unit (arrows).
- Remove hydraulic unit with control module.

ABS Control Module, Removing From Hydraulic Unit
- Disconnect electrical connector for hydraulic pump motor from control module.





- Remove bolts (arrows) from control module and remove control module.

Note:





^ When removing the control module make sure that the hydraulic unit valve dome does not contact the control module solenoid valves.
^ Cover the control module magnet coils with a plastic cover. Do not use rags.
^ After separating the control module and hydraulic unit use transportation protection for the valve dome.

Installing

Note:
^ Only remove the sealing plugs on the new hydraulic unit just before installing the corresponding brake line.
^ If the sealing plugs are removed from the hydraulic unit too early, brake fluid can escape. It can then no longer be guaranteed that the unit is sufficiently filled or adequately bled.
^ When assembling the control module and hydraulic unit, be sure that the hydraulic unit valve dome does not come, in contact with the control module solenoid valves.

- Using new bolts, install control module to hydraulic unit. Do not tighten more than max. 4 Nm (35 inch lbs.).
- Re-connect electrical connector for hydraulic pump motor.
- Install ABS unit to bracket.

Note:
Hand-tighten bolts at first to make attaching the individual brake lines easier.

- After tightening brake lines, tighten hydraulic unit.
- Continue installation in reverse order of removal.
- Bleed brake system. Refer to Brake Bleeding.
- Enter radio code.
- Code control module.