This procedure replaces the ABS module (hydraulic control unit) on a 2015-2020 Ford F-150 with 3.5L EcoBoost engine, including brake line disconnection, module replacement, and complete system bleeding.

Warnings

Tools required

Parts

• ABS hydraulic control unit × 1 — Motorcraft AB-3408 or equivalent OEM
• Brake line sealing washers × 4 — Use OEM specification
• ABS module mounting gasket (if equipped) × 1 — Use OEM specification

Fluids

• Motorcraft DOT 4 LV Brake Fluid — 1 qt

Preparation

1. Park vehicle on level surface and engage parking brake. Chock rear wheels securely.
2. Disconnect negative battery terminal and wait 2 minutes for airbag system to discharge.
3. Remove engine cover if present to access battery and fuse box area.
4. Use fluid extractor or turkey baster to remove as much brake fluid as possible from master cylinder reservoir to minimize spillage.
5. Raise front of vehicle and support securely on jack stands rated for vehicle weight. Never work under a vehicle supported only by a jack.
6. Remove front wheels to provide access for bleeding procedure later.
7. Place large catch pan under ABS module location (driver side frame rail near master cylinder) to catch brake fluid spills.
8. Have brake line plugs ready to immediately cap brake lines when disconnected to minimize fluid loss and contamination.

Procedure

1. 1

   Locate and identify ABS module
   The ABS hydraulic control unit is mounted on the driver side frame rail near the master cylinder and brake booster. It is a rectangular aluminum block with 4 brake lines entering from the top and an electrical connector on the side. Verify you have the correct replacement module by comparing connector configuration and mounting pattern.
2. 2

   Disconnect ABS module electrical connector
   Press the release tab on the ABS module electrical connector and carefully pull straight back to disconnect. Do not pull on wires. Inspect connector pins for corrosion or damage. If connector is corroded, clean with electrical contact cleaner and allow to dry completely before reassembly.
   ⚠Battery must be disconnected before unplugging ABS module to prevent DTC codes and potential module damage.
3. 3

   Disconnect brake lines from ABS module
   Using a flare nut wrench, carefully loosen each of the 4 brake line fittings at the ABS module. Work slowly to avoid rounding off the soft brass fittings. Once loosened, unthread by hand and immediately install brake line plugs or caps to prevent fluid loss and contamination. Label each line with tape indicating position (LF, RF, LR, RR) to ensure correct reinstallation. Note the routing and positioning of brake lines for reassembly.
   ⚠️Brake fluid will immediately begin draining when lines are disconnected. Have catch pan positioned and brake line plugs ready. Do not allow dirt or debris to enter open brake lines or module ports.
4. 4

   Remove ABS module mounting bolts
   Remove the mounting bolts securing the ABS module to the bracket on the frame rail. Support the module with one hand while removing the final bolt as it is heavy and will drop. Carefully lower the old module and place in catch pan to drain remaining fluid. Note the orientation and position of any spacers, brackets, or gaskets for reinstallation.
   ⚠ABS module weighs approximately 5-7 pounds and is awkward to handle. Support module to prevent it from falling and damaging brake lines or components below.
   Torque spec

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

   Prepare new ABS module for installation
   Remove protective caps from brake line ports on new ABS module. Compare new module to old module to verify correct replacement. Check that all mounting holes align and electrical connector matches. Install new sealing washers on all four brake line ports. Do not reuse old washers as they will leak.
   ⚠New ABS modules may contain preservative oil in the ports. Wipe clean with lint-free cloth before installation to prevent contamination of brake system.
6. 6

   Install new ABS module to mounting bracket
   Position new ABS module onto mounting bracket, ensuring any gasket or spacer is properly seated. Install mounting bolts and torque to specification in a cross-pattern to ensure even seating. Verify module is secure and properly aligned with brake line ports accessible.
   Torque spec

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

   Reconnect brake lines to ABS module
   Remove plugs from brake lines and module ports. Inspect brake line flare seats for damage or debris and clean if necessary. Thread each brake line fitting into the correct port by hand, ensuring threads engage smoothly without cross-threading. Once all fittings are hand-tight, use flare nut wrench to torque each fitting to specification in sequence. Double-check that each line is connected to the correct port per your labeling.
   ⚠️Cross-threaded or improperly torqued brake line fittings will leak and cause complete brake failure. If a fitting does not thread smoothly by hand, do not force it. Remove, inspect, and restart.
   Torque spec

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

   Reconnect electrical connector
   Align ABS module electrical connector and push firmly until you hear and feel a positive click. Gently pull back on connector to verify it is fully seated and locked. Inspect connection to ensure no pins are bent or misaligned.
9. 9

   Refill brake fluid reservoir
   Fill master cylinder reservoir to MAX line with fresh Motorcraft DOT 4 LV brake fluid from a sealed container. Keep reservoir filled above MIN line throughout entire bleeding procedure. Monitor fluid level constantly during bleeding and refill as needed.
   ⚠️Never allow master cylinder reservoir to run empty during bleeding or air will enter the system requiring additional bleeding of master cylinder and ABS module.
10. 10

    Perform manual brake bleeding sequence
    Bleed brake system in this sequence: RR, LR, RF, LF. At each wheel, attach bleeder hose to bleeder screw and submerge other end in clean brake fluid in clear container. Have assistant pump brake pedal 5 times and hold. Open bleeder screw 1/2 turn, allow fluid to flow until pedal reaches floor, then close bleeder screw before releasing pedal. Repeat until fluid runs clear with no air bubbles. Torque bleeder screw to specification after each wheel is complete. Refill master cylinder reservoir after each wheel.
    ⚠Manual bleeding alone is insufficient after ABS module replacement. This step only removes bulk air. Scan tool cycling is required to purge air from ABS module internal valves.
    Torque spec

    Bleeder Screw16 Nm (12 lb-ft)
11. 11

    Perform scan tool ABS automated bleeding
    Connect scan tool capable of bidirectional ABS control (Ford IDS, Forscan with appropriate license, or equivalent professional tool). Navigate to ABS module and select 'Automated Bleed' or 'ABS Bleed Cycle' function. The scan tool will cycle ABS solenoid valves to purge air trapped in the module. During this process, you will hear rapid clicking from the ABS module - this is normal. Follow scan tool prompts to bleed specific wheels when commanded. Typically requires 2-3 complete automated cycles. Continuously monitor and refill brake fluid reservoir during this process.
    ⚠️This step is absolutely mandatory and cannot be skipped. ABS modules contain internal check valves that trap air which cannot be removed by manual bleeding alone. Failure to perform automated bleeding will result in spongy pedal and potential brake failure during ABS activation.
12. 12

    Verify brake pedal feel and perform final checks
    With engine off, pump brake pedal 20-30 times. Pedal should become firm and hold pressure. If pedal is spongy or sinks slowly, repeat bleeding procedure. Start engine and verify brake pedal does not sink with constant pressure applied for 30 seconds. Check all brake line connections at ABS module for leaks. Inspect ground under vehicle for any brake fluid drips.
    ⚠️A spongy or sinking brake pedal indicates air remains in the system or a leak is present. Do not operate vehicle until proper pedal feel is achieved and all leaks are corrected.
13. 13

    Reinstall wheels and perform final torque
    Reinstall front wheels and torque lug nuts in star pattern to specification. Lower vehicle from jack stands. With vehicle on ground, re-torque lug nuts in star pattern to final specification.
    Torque spec

    Wheel Lug Nuts156 Nm (115 lb-ft)
14. 14

    Clear ABS codes and verify system operation
    Using scan tool, clear any stored ABS diagnostic trouble codes. Turn ignition on and verify ABS warning light illuminates briefly during bulb check, then extinguishes. If ABS light remains on, retrieve codes and diagnose before operating vehicle. Reconnect battery negative terminal.
    ⚠️If ABS warning light remains illuminated after clearing codes, the system has detected a fault. Do not operate vehicle until fault is diagnosed and corrected.

Reassembly

1. Fill brake fluid reservoir to MAX line with fresh DOT 4 LV fluid
2. Ensure all brake line fittings are torqued to specification and show no signs of leakage
3. Verify ABS module electrical connector is fully seated and locked
4. Confirm all wheels are installed and lug nuts torqued properly
5. Reinstall engine cover if removed during preparation

Verification

• With engine running, verify firm brake pedal with no sinking or sponginess during sustained pressure application
• Perform low-speed test drive in safe area, verifying normal brake operation and firm pedal feel
• Perform moderate braking from 15-20 mph to verify ABS activation occurs normally without unusual noise or vibration
• Verify ABS warning light remains off during test drive and after restart
• Recheck all brake line connections at ABS module for any signs of seepage or leaks after test drive
• Use scan tool to verify no ABS codes are present after test drive
• Check brake fluid level is at MAX line after test drive, top off if needed
• If any abnormality is detected during verification, do not return vehicle to normal service until issue is fully diagnosed and corrected

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