This procedure covers the removal and replacement of the ABS hydraulic control unit (HCU) assembly on a 2021-2024 Ford F-150 with 3.5L EcoBoost V6 engine, including brake line disconnection, module replacement, and system bleeding.

Warnings

Tools required

Parts

• ABS hydraulic control unit (HCU) × 1 — Use OEM Ford part or equivalent
• Brake line sealing washers × 4 — Copper crush washers for brake lines
• Motorcraft DOT 4 LV Brake Fluid × 2 — PM-20

Fluids

• Motorcraft DOT 4 LV Brake Fluid — 2 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Turn ignition off but do NOT disconnect battery (electronic parking brake system requires power)
3. Pump brake pedal 25-30 times with ignition off to relieve residual ABS system pressure
4. Remove brake fluid reservoir cap and extract fluid to minimum line using turkey baster to prevent overflow during line disconnection
5. Raise and support front of vehicle on jack stands at frame rails
6. Remove both front wheels
7. Place absorbent pads or drain pan under ABS module location (driver side of engine bay, near master cylinder)
8. Clean area around ABS module and brake line fittings with brake cleaner to prevent contamination

Procedure

1. 1

   Access ABS hydraulic control unit
   Locate the ABS HCU on the driver side of the engine compartment, mounted near the brake master cylinder. Remove any plastic covers or air intake components blocking access. On 2021-2024 F-150 models, you may need to remove the engine cover and move aside wiring harnesses for clear access to the module and brake lines.
2. 2

   Disconnect electrical connector
   Locate the main electrical connector on the ABS HCU. Press the locking tab and carefully disconnect the connector. Secure the connector away from the work area to prevent brake fluid contamination. Inspect connector terminals for corrosion; clean if necessary before reassembly.
3. 3

   Label and disconnect brake lines
   Using a permanent marker or tape, label each brake line at the HCU (LF, RF, LR, RR) to ensure correct reconnection. Position catch container under fittings. Using flare nut wrenches, carefully loosen and disconnect all four brake lines from the ABS module. Immediately plug or cap open lines to minimize fluid loss and prevent contamination. Expect significant fluid drainage.
4. 4

   Remove ABS module mounting bolts
   Locate the mounting bolts securing the ABS HCU to its bracket. Typically there are two or three bolts. Remove the mounting bolts and carefully lift the ABS module away from the vehicle. Keep module upright to minimize fluid spillage. Have shop towels ready to catch residual brake fluid.
   Torque spec

   Mounting Bolts31 Nm (23 lb-ft)
5. 5

   Prepare new ABS module
   Remove new ABS HCU from packaging. Verify part number matches original unit. Remove protective caps from brake line ports. Install new copper sealing washers on all four brake line fittings (discard old washers). Ensure mounting surface on bracket is clean and free of debris.
6. 6

   Install new ABS module
   Position new ABS HCU onto mounting bracket, aligning mounting holes. Install mounting bolts and torque to specification. Ensure module is seated flush against bracket before final torquing.
   Torque spec

   Mounting Bolts31 Nm (23 lb-ft)
7. 7

   Reconnect brake lines
   Using your labels from disassembly, thread each brake line into the correct port on the new ABS module. Start all fittings by hand to ensure proper thread engagement. Once hand-tight, use flare nut wrench to torque each fitting to specification. Do not overtighten as this can damage the fittings or sealing washers.
   Torque spec

   Line Fittings23 Nm (17 lb-ft)
8. 8

   Reconnect electrical connector
   Reconnect the main electrical connector to the ABS HCU. Ensure connector locks securely with an audible click. Verify locking tab is fully engaged. Reinstall any wiring harness clips or brackets that were removed for access.
9. 9

   Fill brake fluid reservoir
   Fill brake fluid reservoir to MAX line with fresh Motorcraft DOT 4 LV brake fluid from a sealed container. Keep reservoir filled above MIN line throughout the bleeding process. Check reservoir level frequently during bleeding to prevent air introduction.
10. 10

    Perform manual brake bleeding
    Starting with the wheel farthest from master cylinder (RR, LR, RF, LF sequence), perform conventional two-person brake bleeding at each wheel. Have assistant pump brake pedal 3-5 times and hold pressure. Open bleeder screw briefly to expel fluid and air, then close before pedal reaches floor. Repeat until fluid flows clear without bubbles. Torque bleeder screws to specification after bleeding each corner.
    ⚠Do not allow brake pedal to go to floor during bleeding as this can damage master cylinder seals.
    Torque spec

    Bleeder Screw10 Nm (7 lb-ft)
11. 11

    Perform ABS system bleeding with scan tool
    Connect scan tool with ABS bleeding capability. Navigate to ABS system bleeding function. Follow scan tool prompts to cycle ABS solenoids and valves. This typically involves activating each solenoid while bleeding at wheels. Repeat manual bleeding sequence at all four wheels during scan tool activation. Monitor brake fluid level constantly and refill as needed. Continue until all air is purged and brake pedal is firm.
    ℹ️ABS module contains internal valves that trap air; scan tool activation is required to open these valves for complete bleeding.
12. 12

    Verify brake system operation
    With engine running, pump brake pedal several times. Pedal should be firm with normal height. Check for leaks at all brake line connections on ABS module. Start engine and verify ABS warning light extinguishes after bulb check. Test ABS function using scan tool active tests if available.
13. 13

    Reinstall wheels and lower vehicle
    Reinstall front wheels and torque lug nuts in star pattern to specification. Lower vehicle to ground and perform final lug nut torque check. Reinstall any engine covers or components removed for access.
    Torque spec

    Wheel Lug Nuts140 Nm (103 lb-ft)

Reassembly

1. Ensure all brake line fittings are torqued to specification and show no signs of leakage
2. Verify brake fluid level is at MAX line in reservoir
3. Confirm ABS warning light operates normally (illuminates with key on, extinguishes after engine start)
4. Double-check that all electrical connectors are fully seated and locked
5. Verify all wheels are torqued properly in star pattern

Verification

• Start engine and verify ABS warning light extinguishes within 3-5 seconds
• Pump brake pedal with engine running - pedal should be firm and consistent with no sponginess
• Perform low-speed test drive in safe area, verifying normal brake operation
• Perform ABS activation test at low speed (15-20 mph) on safe surface to verify ABS pulses normally
• Use scan tool to check for any ABS fault codes; clear codes if only related to old module
• Recheck all brake line connections for leaks after test drive
• Verify brake fluid level after test drive and top off if needed
• Inspect ground under vehicle for any brake fluid leaks after vehicle sits overnight

More procedures for this vehicle