Bosch 5.3 ABS System

Component Notes and Information

NOTE:
^ During service procedures, refer to the illustration above and the information below
^ The hydraulic unit is located in the left front side of the engine compartment.
^ When removing and installing the brake lines/hoses, ensure they are marked and installed as per the markings on the hydraulic unit.
^ Brake lines/hoses must not be interchanged when reconnecting.

1 Tandem brake master cylinder
- With tandem brake servo unit
2 Brake line
- Master brake cylinder/secondary piston circuit to hydraulic unit
3 Brake line
- Brake master cylinder/primary piston circuit to hydraulic unit
4 Brake line
- Hydraulic unit to right front brake caliper
5 Brake line
- Hydraulic unit to right rear brake caliper
6 Brake line
- Hydraulic unit to left rear brake caliper
7 Brake line
- Hydraulic unit to left front brake caliper
8 Hex nut
- Tighten to: 8 Nm (70 inch lb)
9 Cover
10 ABS/EDL hydraulic unit
- Bolted to control module
- Only replace as a complete unit
11 Hex nut
- Tighten to: 12 Nm (9 ft lb)
12 Mounting bracket
13 Bolt
- Tighten to: 8 Nm (70 inch lb)

Special Tools Required





- VAG 1331 Torque wrench





- VAG 1869/2 Brake pedal loading device

Location
- The control module is bolted to the hydraulic unit and is located on the left side in the engine compartment.

CAUTION: Do not bend the brake pipes in the area of the hydraulic unit.

Removal
- Obtain radio code on vehicles with coded radio.
- Disconnect battery ground strap.





- Release control module connector (arrow -1-) and remove (arrow -2-).
- Remove as much brake fluid as possible from brake fluid reservoir using a suction bottle.
- Position brake pedal loading device from VAG 1869/2.
- Depress brake pedal with brake pedal depressor.
- Connect bleeder bottle hose to left front brake caliper bleed screw and open bleed screw.
- Close left front caliper bleed screw.
- Place sufficient lint-free cloths under hydraulic unit.
- Disconnect brake lines on hydraulic unit and seal lines and threaded holes with plugs.
- Remove hydraulic unit.

Installation

NOTE:
^ Only remove sealing plugs on the hydraulic unit when the relevant brake line is going to be connected.
^ If the sealing plugs are removed too early brake fluid can escape, it can then no longer be guaranteed that the hydraulic unit is sufficiently filled or adequately bled.

- Further installation is carried out in the reverse sequence
- Refer to bleeding brake system. Service and Repair
- Tighten the following to:
- Brake lines to ABS hydraulic unit:
Thread M10x1 15 Nm (11 ft lb)
Thread M12x1 15 Nm (11 ft lb)