ABS Module

Remove and replace the ABS/ESP hydraulic control unit, including brake line disconnection, module replacement, brake bleeding, and system recalibration.

Warnings

Tools required

Parts

• ABS/ESP hydraulic control unit (M275 engine specific) × 1 — A2215452632 or equivalent
• ABS module to brake line sealing washers × 6 — Use OEM specification
• ABS module wiring harness connector (if damaged) × 1 — Use OEM specification

Fluids

• DOT 4+ Brake Fluid — 2 qt

Preparation

1. Verify the replacement ABS module is specifically for M275 engine vehicles (2007-2013 S65 AMG). Modules from other S-Class models are NOT compatible.
2. Ensure Star Diagnosis (SDS) or Xentry diagnostic system is available, properly licensed, and updated to latest software version.
3. Park vehicle on level surface and ensure transmission is in Park with parking brake released.
4. Disconnect negative battery terminal and wait 10 minutes for SBC system capacitor discharge.
5. Remove front underbody panels to access ABS module from below (module is located in front of engine, driver side of radiator support).
6. Connect diagnostic system and document all fault codes. Perform preliminary ABS system test and save configuration data.
7. Place clean drain pans under ABS module location to catch brake fluid.
8. Prepare brake line caps and have new sealing washers ready for immediate installation.

Procedure

1. 1

   Deactivate ABS hydraulic system
   Using Star Diagnosis, navigate to ABS/ESP control unit. Execute 'Hydraulic Unit Deactivation' function. This relieves residual pressure (up to 2900 PSI) stored in the accumulator. Wait for system confirmation that pressure is fully relieved before proceeding. Do NOT skip this step or attempt manual depressurization.
   ⚠️Failure to properly depressurize can cause brake lines to eject with extreme force when loosened, causing severe injury.
2. 2

   Disconnect ABS module electrical connectors
   Locate the two main electrical connectors on top of the ABS module (one 38-pin and one 24-pin connector). Press release tabs and carefully pull connectors straight up. Inspect connector pins for corrosion or damage. If pins are bent or corroded, replacement harness connector will be required.
   ⚠Do not pull on wires. These connectors use secondary locking mechanisms that must be released before removal.
3. 3

   Mark and disconnect brake lines
   Using a permanent marker or paint pen, clearly mark each of the six brake lines at the ABS module with their positions (FL-front left, FR-front right, RL-rear left, RR-rear right, M1-master cylinder feed, M2-master cylinder return). Using flare nut wrenches only, loosen each brake line fitting 1/4 turn while supporting the line. Have an assistant ready with caps to immediately seal each line as it is removed. Remove and discard old sealing washers from each fitting.
   ⚠Use only flare nut wrenches. Standard open-end wrenches will round off the soft brass fittings and require brake line replacement.
   ⚠Brake fluid will drain immediately upon loosening. Cap lines within 5 seconds to minimize air introduction and fluid loss.
   Torque spec

   Brake Line Fittings15 Nm (11 lb-ft)
4. 4

   Remove ABS module mounting bolts
   Locate the four ABS module mounting bolts securing the unit to the bracket (two on top, two on bottom accessed from underneath). Remove all four bolts and retain them if they are in good condition. Support the module weight while removing the final bolt as the unit weighs approximately 15 lbs.
   Torque spec

   ABS Module Bolts10 Nm (7 lb-ft)
5. 5

   Remove ABS module assembly
   Carefully lower the ABS module assembly, ensuring all brake lines are fully disconnected and clear. Tilt the module slightly to navigate it past surrounding components. Place the old module on a clean work surface with brake ports facing up to minimize fluid drainage. Inspect the mounting bracket for cracks or damage.
   ⚠Module will continue to drip brake fluid. Keep away from painted surfaces and electrical components.
6. 6

   Prepare new ABS module
   Remove protective caps from all six brake ports on the new module. Verify part number matches the old unit exactly. Install new sealing washers onto each of the six brake line fittings (do not reuse old washers). Apply a small amount of clean DOT 4+ brake fluid to each sealing washer surface.
   ℹ️New modules are shipped dry. Do NOT attempt to pre-fill the module - this will be done automatically during the bleeding procedure.
7. 7

   Install new ABS module
   Position the new ABS module onto the mounting bracket, aligning all mounting holes. Install all four mounting bolts finger-tight first to ensure proper alignment. Torque bolts in a cross pattern (top left, bottom right, top right, bottom left) to specification.
   ⚠Do not overtighten ABS module bolts. The aluminum housing can crack if torque exceeds 12 Nm.
   Torque spec

   ABS Module Bolts10 Nm (7 lb-ft)
8. 8

   Reconnect brake lines
   Referring to your position marks from Step 3, thread each brake line onto the correct port by hand until finger-tight. Verify each line is started straight (not cross-threaded). Using flare nut wrenches, torque each fitting to specification in the following order: M1 master cylinder feed, M2 master cylinder return, FL, FR, RL, RR. Wipe away any spilled brake fluid immediately.
   ⚠Cross-threading brake fittings will require brake line replacement. Thread fittings carefully by hand first to ensure proper engagement.
   Torque spec

   Brake Line Fittings15 Nm (11 lb-ft)
9. 9

   Reconnect electrical connectors
   Clean connector sealing surfaces if necessary. Align and press both electrical connectors (38-pin and 24-pin) onto the ABS module until you hear distinct clicks indicating full engagement. Verify secondary locking tabs are fully seated. Gently tug on each connector to confirm secure connection.
   ℹ️Partially seated connectors will cause multiple fault codes and may prevent proper system operation without obvious symptoms.
10. 10

    Reconnect battery and perform initial communication test
    Reconnect the negative battery terminal. Using Star Diagnosis, attempt to establish communication with the ABS/ESP control unit. The new module should respond but will show numerous fault codes (this is normal). Do NOT clear codes yet. Verify the module part number and software version displayed match your vehicle specifications.
    ⚠If diagnostic system cannot communicate with the new module, immediately disconnect battery and verify all electrical connections before attempting to start the vehicle.
11. 11

    Perform ABS system bleeding procedure
    Using Star Diagnosis, execute 'ABS/ESP Hydraulic Unit Bleeding' function. Connect pressure bleeder to brake fluid reservoir with 20 PSI pressure. Follow on-screen prompts exactly - the system will automatically cycle valves and motors in specific sequences. The procedure takes approximately 15-20 minutes. Monitor fluid level constantly and refill reservoir as needed. When complete, the diagnostic system will confirm successful bleeding.
    ⚠️Do NOT attempt manual bleeding or use aftermarket scan tools. The ABS module contains internal valves and pumps that MUST be cycled in a specific sequence or air will remain trapped in the system, causing brake failure.
    ⚠Maintain pressure bleeder at 15-20 PSI only. Higher pressure can damage ABS solenoid valves.
12. 12

    Bleed brake calipers
    Following ABS module bleeding, bleed each brake caliper in this sequence: RR, RL, FR, FL. At each caliper, attach clear hose to bleeder screw and submerge end in clean brake fluid. Open bleeder screw 1/2 turn and allow fluid to flow until completely free of air bubbles (approximately 4-6 oz per caliper). Close bleeder screw to specification before releasing brake pedal or pressure bleeder.
    ⚠Always tighten bleeder screw before releasing pressure. Reverse sequence will draw air back into the system.
    Torque spec

    Bleeder Screw18 Nm (14 lb-ft)
13. 13

    Program and calibrate ABS module
    Using Star Diagnosis, execute 'ABS/ESP Control Unit Programming' function. The system will download the correct software and configuration for your specific vehicle VIN. This process takes 20-40 minutes - do not interrupt or disconnect. After programming completes, execute 'Steering Angle Sensor Calibration' and 'Brake Pressure Sensor Calibration' functions. Follow all on-screen instructions exactly.
    ⚠️Programming must not be interrupted. Ensure battery is fully charged and charger is connected. Power loss during programming will render the module inoperable and may damage the vehicle CAN network.
14. 14

    Clear fault codes and verify system operation
    Clear all fault codes from ABS/ESP control unit. Turn ignition off, then on. Verify ABS warning lamp illuminates briefly then extinguishes. Verify ESP, BAS, and brake warning lamps all extinguish. If any lamps remain illuminated, retrieve and address fault codes before proceeding. Reinstall underbody panels.
    ⚠Any illuminated warning lamps indicate incomplete installation or calibration. Do NOT operate vehicle until all warnings are resolved.

Reassembly

1. Reinstall all front underbody panels and verify all fasteners are secure.
2. Top off brake fluid reservoir to MAX mark using only DOT 4+ specification brake fluid.
3. Verify all tools and rags have been removed from engine compartment.
4. Double-check all six brake line fittings are torqued to specification with no visible leaks.

Verification

• Start engine and verify ABS, ESP, BAS, and brake warning lamps all extinguish within 3 seconds. If any lamp remains on, retrieve fault codes immediately.
• With engine running, firmly depress brake pedal and hold for 30 seconds. Pedal should remain firm with no sinking. Any pedal travel indicates air in system - repeat bleeding procedure.
• Perform test drive in safe area at low speed (under 15 mph). Verify brake pedal feel is normal and vehicle stops straight without pulling.
• Perform ABS activation test at 20 mph on dry pavement with firm brake application. You should feel ABS pulsation and hear pump activation. Verify ESP light does not illuminate.
• After test drive, inspect all six brake line connections at ABS module for any signs of seepage or wetness. Any fluid indicates improper torque - tighten to specification.
• Using Star Diagnosis, perform final system scan and verify zero fault codes in ABS/ESP control unit.
• Perform steering angle sensor verification by turning steering wheel lock-to-lock with engine running. Star Diagnosis should show smooth angle changes from -720 to +720 degrees.
• Road test vehicle at highway speeds (if legal and safe) to verify ESP and stability systems function normally during lane changes and moderate cornering.

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