ABS Pump

Replace the ABS hydraulic pump/module assembly on a 2007-2013 Mercedes-Benz S65 AMG, including brake fluid evacuation, hydraulic unit removal, installation, and system bleeding.

Warnings

Tools required

Parts

• ABS Hydraulic Pump Assembly (ESP/ABS Module) × 1 — A0054319712 or equivalent
• Brake line sealing washers × 6 — Use OEM specification
• ABS module mounting grommets × 3 — Use OEM specification

Fluids

• DOT 4+ Brake Fluid — 2 qt

Preparation

1. Park vehicle on level surface and apply parking brake
2. Turn ignition off and remove key. Wait 5 minutes for system capacitors to discharge
3. Disconnect negative battery terminal and wait additional 10 minutes
4. Open hood and locate ABS hydraulic unit on left side of engine bay near fender
5. Remove engine cover and left side engine compartment trim panels for access
6. Place drip pan and absorbent material under ABS unit area
7. Pump brake pedal 20-30 times with ignition off to depressurize hydraulic accumulator

Procedure

1. 1

   Evacuate brake fluid from reservoir
   Use brake fluid evacuation tool to remove as much fluid as possible from the brake fluid reservoir. This minimizes spillage during brake line disconnection. Do not allow reservoir to completely empty during this process to prevent introducing air into lines prematurely.
2. 2

   Disconnect electrical connectors
   Locate the main ABS/ESP module electrical connector on top of the hydraulic unit. Press the locking tab and carefully disconnect the large multi-pin connector. On S65 AMG models, there is a secondary connector for the pressure sensor - disconnect this as well. Note connector orientation for reinstallation.
3. 3

   Label and disconnect brake lines
   Using a marker or tape, label all six brake lines connected to the ABS pump (four wheel circuits, one master cylinder feed, one return). Clean around each fitting with a wire brush. Using appropriate flare nut wrenches (10mm/11mm), carefully loosen and disconnect each brake line. Work slowly to avoid rounding off fittings. Immediately cap or plug open lines to prevent fluid loss and contamination.
   ⚠Brake line fittings are made of soft metal and easily damaged. Use only proper flare nut wrenches, not standard open-end wrenches.
4. 4

   Remove ABS pump mounting fasteners
   Locate the three mounting bolts securing the ABS hydraulic unit to its bracket. These are typically 13mm head bolts accessed from the top and front of the unit. Remove all three mounting bolts completely. Support the unit with one hand as you remove the final bolt.
   Torque spec

   Mounting Bolts37 Nm (27 lb-ft)
5. 5

   Extract ABS hydraulic unit
   Carefully lift the ABS pump assembly straight up and out of the engine compartment. The unit sits on rubber mounting grommets which may stick. Tilt the unit slightly to maneuver it past surrounding components. Have shop towels ready as residual brake fluid will drain from the open ports. Place the old unit in drip pan.
6. 6

   Prepare new ABS pump for installation
   Remove the new ABS pump from packaging and verify part number matches original unit. Install new sealing washers on all brake line ports. Verify all electrical connector seals are properly seated. Check that new rubber mounting grommets are installed in the bracket if removed with old unit.
7. 7

   Install new ABS hydraulic unit
   Guide the new ABS pump into position in the mounting bracket, ensuring it seats properly on all three rubber grommets. Align the unit so brake line ports are accessible and properly oriented. Install the three mounting bolts finger-tight initially, then torque in a cross pattern to specification.
   Torque spec

   Mounting Bolts37 Nm (27 lb-ft)
8. 8

   Reconnect brake lines
   Starting with the master cylinder feed line, thread each brake line into its correct port by hand to prevent cross-threading. Reference your labels from disassembly. Once all lines are hand-started, tighten each fitting to 15 Nm (11 lb-ft) using flare nut wrenches. Work in sequence from master cylinder feed to wheel circuits. Do not overtighten as this can damage fittings.
   ⚠Cross-threaded brake line fittings will result in system failure. Always start fittings by hand and ensure smooth threading before using tools.
9. 9

   Reconnect electrical connectors
   Reconnect the main ABS/ESP module connector to the hydraulic unit, ensuring it seats completely and the locking tab clicks into place. Reconnect the secondary pressure sensor connector. Verify connections are secure with a gentle tug.
10. 10

    Refill brake fluid reservoir
    Fill the brake fluid reservoir to the MAX line with fresh DOT 4+ brake fluid. Use only unopened containers to prevent moisture contamination. Keep reservoir filled above MIN throughout the bleeding process.
11. 11

    Perform initial manual brake bleeding
    Starting with the wheel furthest from the ABS pump (right rear), bleed each wheel circuit in sequence: right rear, left rear, right front, left front. At each wheel, attach bleeder hose to bleeder screw, loosen screw, have assistant slowly depress brake pedal, tighten screw before pedal is released. Repeat until fluid runs clear without bubbles. Torque bleeder screws to specification.
    ⚠Never allow brake fluid reservoir to run below MIN line during bleeding or severe air contamination will occur.
    Torque spec

    Bleeder Screw10 Nm (7 lb-ft)
12. 12

    Reconnect battery and perform ABS system bleeding
    Reconnect the negative battery terminal. Connect Mercedes-Benz Star Diagnostic Scanner. Navigate to ABS/ESP system and select 'Bleed Brake System' function. Follow on-screen prompts which will activate ABS pump motors and cycle solenoid valves. The scanner will direct bleeding sequence at each wheel. This process typically takes 15-20 minutes and may require 1-2 quarts of brake fluid.
    ⚠️ABS system bleeding MUST be performed with factory diagnostic equipment. Failure to properly bleed ABS valves will result in reduced or complete brake failure in emergency situations.
13. 13

    Clear fault codes and verify system operation
    Using the diagnostic scanner, clear all ABS/ESP fault codes stored during the replacement procedure. Verify that no new faults are present. Check that ABS self-test completes successfully. Inspect all brake line connections for leaks with fluid still pressurized.

Reassembly

1. Reinstall all engine compartment trim panels and engine cover removed during preparation
2. Check brake fluid level one final time and top off to MAX line if needed
3. Clean any spilled brake fluid from painted surfaces and components
4. Verify all tools and materials are removed from engine compartment

Verification

• With engine running, verify ABS warning light extinguishes after initial self-test (approximately 3 seconds)
• Perform low-speed test drive in safe area and verify normal brake pedal feel and firmness
• Perform ABS activation test at 20-25 mph on dry pavement with hard braking - verify pulsation and proper ABS operation
• Re-check all brake line connections for leaks after test drive
• Using diagnostic scanner, verify no ABS/ESP fault codes are present and all system components show 'OK' status
• Check brake fluid level after test drive and confirm it remains at proper level
• Document repair and reset service interval for brake fluid if applicable

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