Removing and Installing Hydraulic Modulator
Before beginning any brake work on an ABS-equipped car, it is necessary to relieve pressure in the system. With the engine not running, depress the brake pedal 25 to 35 times or until there is a noticeable increase in pedal effort.
WARNING-
The ABS operates at very high pressure-as much as 210 bar (3045 psi)-and is self-pressurizing. This pressure may be retained in the system even though the car is not running and has not been driven recently. To avoid personal injury, this residual pressure must be dissipated before opening any part of the ABS hydraulic system.
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NOTE-
Two different modulators are installed on cars equipped with ABS. Component parts such as the pump unit or pressure accumulator are not interchangeable. For more information see an authorized Volkswagen parts department.
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To remove:
| 1. | With the engine not running, pump the brake pedal to relieve system pressure as described above. |
| 2. | Make sure the ignition is off, and disconnect the battery ground (-) cable from the battery. Disconnect all electrical harness connectors from the hydraulic modulator. |
| 3. | Remove as much brake fluid as possible from the reservoir, and disconnect all brake lines from the hydraulic modulator. Plug the open ports to prevent contamination. |
| 4. | Working inside the passenger compartment, under the left side of the instrument panel, disconnect the brake pedal from the master cylinder pushrod clevis. |
| 5. | Remove the self-locking hydraulic modulator mounting nuts, and remove the unit from the car. |
Installation is the reverse of removal. Use new self-locking nuts to mount the hydraulic modulator. Torque them to 25 Nm (18 ft. lb.); torque all brake line connections to 15 Nm (11 ft. lb.). After installation the system must be bled of air. See 4.2 Bleeding Brakes..
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