Electronic Brake Control Module: Service and Repair

ABS Control Module And Hydraulic Unit, Removing And Installing
Required Special Tools And Equipment:





^ VAG 1331 Torque wrench or equivalent





^ VAG 1332 Torque wrench or equivalent

Location
The control module is attached to the hydraulic unit and is located on the left side of the engine compartment.

CAUTION!
^ Do not bend brake lines at the hydraulic unit.

Removing
- Obtain radio code for vehicles with coded radio.
- Disconnect battery.





- Remove intake hose -1- and connector -2- from Mass Air Flow (MAF) Sensor.
- Remove bolts -4- and -5-.
- Remove air cleaner as complete unit. Refer to Powertrain Management.
- For vehicles with Diesel engines, remove relay panel above brake booster.

WARNING!
^ Brake fluid is poisonous.
^ 1o draw off brake fluid from the reservoir use a bleeder bottle used only for brake fluid. Never siphon brake fluid by mouth.

Remove as much brake fluid as possible from brake fluid reservoir using a bleeder bolt.
- Install brake pedal depressor from VAG 1238 B or equivalent.
- Connect bleeder bottle hose to left front brake caliper bleeder screw and open bleeder screw. Close bleeder screw.





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

CAUTION!
^ 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 on hydraulic unit.
- Seal brake lines and threaded holes (arrows) with Plugs from repair kit, Part No. 1 HO 698 311 A.





- Remove bolts on hydraulic unit bracket (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.





- Pull control module straight up to remove.

Note:
^ Be sure that the hydraulic unit valve dome is not tilted against the control module solenoid valves.
^ Cover the control module magnetic coils with a plastic covering. Do not use rags.
^ After separating the control module and hydraulic unit, use transportation protection for the valve dome.

Installing

CAUTION
^ Only remove sealing plugs on the new hydraulic unit just before installing the corresponding brake line.
^ M the sealing plugs are removed 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 is not tilted against 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 to make attaching individual brake lines easier

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

Tightening Torques:
Control Module To Hydraulic Unit Max. 4 Nm 35 inch lbs.
Hydraulic Unit Bolt To Bracket 8 Nm 71 inch lbs.
Nut For Brake Master Cylinder To Brake Booster 20 Nm 15 ft. lbs.
Brake Lines To ABS Unit
Thread M10 x 1 15 Nm 11 ft. lbs.
Thread M12 x 1 15 Nm 11 ft. lbs.
Nut To Body 20 Nm 15 ft. lbs.
Cap Nut To Body 20 Nm 15 ft. lbs.