Remove and replace the ABS hydraulic control unit (HCU) module, including brake line disconnection, system bleeding, and electronic control module replacement.

Warnings

Tools required

Parts

• ABS Hydraulic Control Unit (HCU) Module × 1 — 58920-A7600 or equivalent OEM
• Brake line copper washers/gaskets × 4 — Use OEM specification
• DOT 4 Brake Fluid × 2 — Minimum 1 quart for bleeding

Fluids

• DOT 4 Brake Fluid — 2 qt

Preparation

1. Park vehicle on level surface and engage parking brake. Place wheel chocks behind rear wheels.
2. Ensure engine is completely cold before beginning work.
3. Open hood and locate battery in engine compartment. Install battery memory saver if available.
4. Disconnect negative battery terminal and secure cable away from battery post. Wait 3 minutes for airbag system capacitors to discharge.
5. Locate ABS module in engine compartment near master cylinder on driver side firewall.
6. Place drain pan under master cylinder and ABS module area to catch brake fluid spillage.
7. Have minimum 2 quarts of fresh, sealed DOT 4 brake fluid ready for system bleeding.
8. Ensure ABS scanner tool is available and functioning before beginning disassembly.

Procedure

1. 1

   Disconnect ABS module electrical connector
   Locate the large multi-pin electrical connector on the ABS module. Press the locking tab and carefully disconnect the connector. Do not pull on wires. Inspect connector pins for corrosion or damage. If connector is corroded, replacement is recommended to prevent future electrical faults.
2. 2

   Label and disconnect brake lines
   The ABS module has four brake lines connected (one from master cylinder inlet, three outlets to wheel circuits). Use paint marker or tape to clearly label each line position (front left, front right, rear, inlet). Using the 12mm flare nut wrench, carefully loosen each brake line fitting. Turn slowly to avoid rounding off soft brass fittings. Once loose, unthread by hand. Immediately cap open lines with protective caps to prevent fluid loss and contamination. Position catch pan to collect draining fluid.
   ⚠Use only flare nut wrenches on brake line fittings. Standard wrenches will round off the soft brass fittings. If fittings are severely corroded, consider replacing brake lines to prevent future leaks.
   Torque spec

   Brake Line Fittings15 Nm (11 lb-ft)
3. 3

   Remove ABS module mounting bolts
   Locate the two mounting bolts securing the ABS module to the bracket on the firewall. These are 10mm head bolts. Use a 10mm socket to remove both bolts completely. Support the module with one hand while removing the second bolt as the module is heavy (approximately 5 lbs) and filled with brake fluid.
   ⚠The ABS module is heavy and contains residual brake fluid. Support it carefully during removal to prevent dropping and injury or damage to surrounding components.
   Torque spec

   ABS Module Bolts10 Nm (7 lb-ft)
4. 4

   Remove old ABS module
   Carefully lift the ABS module away from the mounting bracket. Tilt the module to drain any residual brake fluid into the catch pan. Inspect the mounting bracket for corrosion or damage. Clean mounting surface with wire brush if necessary. Verify the new replacement module matches the old unit exactly in connector configuration and brake line port positions.
5. 5

   Prepare new ABS module for installation
   Remove protective caps from brake line ports on new ABS module. Inspect all ports for foreign material or shipping debris. Install new copper washers/gaskets on each brake line fitting if provided with module or purchased separately. Apply a small amount of clean brake fluid to the threads of each brake line to ease installation and prevent cross-threading.
   ℹ️Some replacement modules come pre-filled with brake fluid, others are dry. Consult module documentation. Dry modules will require additional bleeding time.
6. 6

   Install new ABS module to bracket
   Position the new ABS module onto the mounting bracket, aligning the bolt holes. Hand-thread both mounting bolts to ensure proper alignment. Once both bolts are started, torque each bolt to specification using a torque wrench. Torque in a cross pattern (alternate between bolts) to ensure even seating.
   ⚠️CRITICAL: ABS module mounting bolts must be torqued to exact specification (10.0 Nm / 7.0 lb-ft). Over-torquing can crack the module housing causing catastrophic brake fluid loss. Under-torquing can allow module movement and brake line fatigue failure.
   Torque spec

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

   Reconnect brake lines
   Remove protective caps from brake lines. Reference your labels from disassembly. Thread each brake line fitting into the correct port on the ABS module by hand for at least 3 full turns to ensure proper engagement and prevent cross-threading. Once all fittings are hand-tight, use the flare nut wrench to torque each fitting to specification. Torque the inlet line first (from master cylinder), then the three outlet lines.
   ⚠️CRITICAL: Brake line fittings must be torqued to exact specification (15.0 Nm / 11.0 lb-ft). Over-torquing can strip soft brass threads or crack the fitting. Under-torquing will cause brake fluid leaks and potential brake failure. Cross-threading will require brake line replacement.
   Torque spec

   Brake Line Fittings15 Nm (11 lb-ft)
8. 8

   Reconnect electrical connector
   Align the electrical connector with the ABS module connector pins. Push firmly until the locking tab clicks into place. Gently tug on the connector to verify it is fully seated and locked. Inspect that no pins are bent or misaligned.
9. 9

   Reconnect battery and perform initial power-up
   Reconnect the negative battery terminal. Hand-tighten the terminal clamp nut securely. Turn the ignition to ON position (do not start engine). The ABS warning light should illuminate on the dashboard and remain on, which is normal before programming. Do not attempt to start or drive the vehicle at this stage.
10. 10

    Bleed brake system - master cylinder and ABS module
    Check master cylinder reservoir and fill to MAX line with fresh DOT 4 brake fluid. Connect ABS scan tool and access ABS bleeding function. Follow scan tool prompts to activate ABS pump and open solenoid valves. This purges air from internal ABS passages. Starting at the wheel furthest from the master cylinder (right rear), then left rear, right front, left front, perform standard brake bleeding at each caliper bleeder screw. Have an assistant pump brake pedal 3-5 times and hold, then open bleeder screw 1/2 turn. Close bleeder before pedal reaches floor. Repeat until fluid flows clear without bubbles. Torque bleeder screws to specification. Check and refill master cylinder frequently during bleeding.
    ⚠️CRITICAL: Improper bleeding will leave air in the system causing spongy pedal feel and reduced braking effectiveness. The ABS module MUST be bled using a scan tool with bidirectional control to cycle internal valves. Manual bleeding alone is insufficient and dangerous.
    ⚠Never allow master cylinder reservoir to run dry during bleeding. This introduces additional air into the system requiring complete re-bleeding. Monitor fluid level constantly.
    Torque spec

    Bleeder Screw13 Nm (10 lb-ft)
11. 11

    Program and initialize ABS module
    Using the ABS scan tool, access the ABS module programming menu. Perform vehicle identification number (VIN) registration to the new module if required. Execute ABS initialization or configuration procedure as prompted by scan tool. This may include automated bleeding sequences, sensor baseline learning, and system self-tests. Clear any diagnostic trouble codes that were set during installation. Verify no active fault codes remain.
    ⚠️CRITICAL: The ABS module will not function correctly without proper programming and initialization. Driving with an unprogrammed module may result in ABS failure or unexpected activation. This step requires professional-grade scan tool capability.
12. 12

    Perform brake pedal feel test
    With engine off, pump brake pedal 20-30 times. Pedal should feel firm after initial travel. Start engine - pedal should drop slightly as brake booster activates, then remain firm. Pedal should not sink slowly to floor under constant pressure. If pedal feels spongy or sinks, additional bleeding is required. Verify ABS warning light extinguishes within 3 seconds of starting engine.
    ⚠️Do not proceed to test drive if brake pedal feels soft, spongy, or sinks to the floor. This indicates air in the system or a leak. Repeat bleeding procedure or inspect all connections for leaks.

Reassembly

1. Torque all components to exact specifications listed. Do not estimate or reuse torque values from other vehicles.
2. Inspect all brake line connections for fluid seepage after bleeding. Wipe dry and monitor for several minutes.
3. Verify master cylinder reservoir is filled to MAX line with DOT 4 fluid. Install reservoir cap securely.
4. Clean any spilled brake fluid from painted surfaces immediately with water to prevent paint damage.
5. Ensure all tools and parts are removed from engine compartment before closing hood.

Verification

• With engine running, verify ABS warning light is OFF. If light remains on, retrieve diagnostic codes with scan tool and address faults.
• Perform brake line leak check: with assistant pressing brake pedal firmly, inspect all four brake line connections at ABS module for fluid seepage. Any leakage requires immediate re-torquing or component replacement.
• Conduct low-speed brake test in safe, controlled environment (empty parking lot): at 5 mph, apply brakes gently to verify proper function and firm pedal feel. At 10-15 mph, perform slightly harder stop to verify system response.
• Perform ABS function test on safe, dry pavement: at 20-25 mph on a straight path with no traffic, apply hard braking to activate ABS. Verify pulsation in pedal and proper ABS operation. If ABS does not activate or warning light illuminates, do not drive vehicle - diagnose and repair.
• After successful test drive, re-check master cylinder fluid level and top off if necessary. Inspect all connections one final time for leaks.
• Before returning to normal operation, inform driver that brake system work was performed and initial caution is advised for first 50 miles of driving.

More procedures for this vehicle