Table of contents: Removal ↓ Installation ↓
Hydraulic block N55 with used L 04 1. Hydraulic unit ABS "N55" used ABS "L 04". Hydraulic unit N55 and control unit L 04 cannot be separated. Installation location: in the engine compartment, front left. Hydraulic unit "N55" with integrated pressure sensor in the brake system G201 and control unit "L 04" form a hydraulic control unit. The components of the unit cannot be separated. Do not disconnect the plug connector until the end of the self-diagnosis. Before disconnecting the plug connector, switch off the ignition. Pressure sensor in the brake system "G201" is integrated into the hydraulic unit "N55" and cannot be replaced; 2. ESP bracket. Removing the bracket is prohibited.; 3. Plug connector of the control unit L 04; 4. Brake line to the master cylinder. 14 Nm; 5. Brake line to the master cylinder. 14 Nm; 6. Brake lines. Connects the hydraulic unit and the front right brake caliper, 14 N·m. Connects the hydraulic unit and the front left brake caliper, 14 N·m. Connects the hydraulic unit and the rear left brake caliper, 14 N·m. Connects the hydraulic unit and the rear right brake caliper, 14 N·m
Removal
Read and record the control unit modification. Use the diagnostic complex "VAS 5051B" or "VAS 5052" for this. Disconnect the battery, taking into account the coding of the radio. Install the spacer "V.A.G 1869/2" between the brake pedal and the driver's seat, pressing the brake pedal at least 60 mm.
This closes the master cylinder valves and the brake fluid reservoir does not remain empty. Connect the bleeder tank hose to the bleeder nipple of the front left brake caliper. Connect the bleeder tank hose to the bleeder nipple of the rear left brake caliper. Open the bleeder nipple of the front left and rear left brake caliper to relieve pressure in the hydraulic unit "N55". Close the front left and rear left bleeder nipple. Do not remove the spacer. VAG 1869/2.
Move the lock "1" of the control unit plug connector to the lower position. Move the locking bracket "in the direction of the arrow" and disconnect the plug. Make sure that brake fluid does not get into the control unit connector housing. This may lead to corrosion of the contacts and, as a result, to failure of the system.
Clean the contaminated plug housing thoroughly with compressed air. To collect the escaping brake fluid, simply place a lint-free rag under the used "L 04" and the "N55" hydraulic unit. Mark the brake lines for subsequent installation. Loosen the bolts securing the brake lines running from the N55 hydraulic unit to the master brake cylinder. Loosen the bolts securing the remaining "arrow" brake lines from the "N55" hydraulic unit.
Close the brake lines and threaded holes with plugs from the repair kit. Carefully remove the "N55" hydraulic unit from the used "L 04" from the bracket upwards. When removing the ESP control unit from the bracket, make sure that the rubber stops do not fall into the engine compartment. Place the "N55" hydraulic unit from the used "L 04" down on a clean, level surface. After removing the "L 04" control unit and the "N55" hydraulic unit, it is necessary to close the threaded holes and brake lines with plugs.
Installation
Installation is carried out in reverse order, while taking into account the following: for servicing, the hydraulic unit "N55" must be filled with brake fluid. The plugs from the new hydraulic unit "N55" should only be removed when the corresponding brake line is installed. If the plugs are removed from the hydraulic unit "N55" before installing the corresponding brake line, brake fluid will leak out. In this case, sufficient bleeding of the brake system is not guaranteed. All rubber stops must be inserted into the bracket. Press down on the hydraulic unit "N55" with the used "J104" and insert it into the bracket. When installing