ABS Pump

This procedure covers the removal and replacement of the ABS hydraulic control unit (HCU/pump) on a 2007 Ram 3500 with 5.9L Cummins diesel engine.

Warnings

Tools required

Parts

• ABS Hydraulic Control Unit (HCU/Pump) × 1 — Use OEM specification
• Brake fluid DOT 3 × 2 — Use OEM specification

Fluids

• DOT 3 brake fluid — 2 qt

Preparation

1. Park vehicle on level ground and place transmission in park with parking brake engaged
2. Disconnect negative battery cable and wait 2 minutes for airbag system to discharge
3. Remove brake fluid from master cylinder reservoir using turkey baster or fluid extractor to prevent overflow during line disconnection
4. Spray all brake line fittings at ABS module with penetrating oil and allow to soak for 10-15 minutes
5. Prepare clean workspace and have brake line plugs ready to prevent fluid loss and contamination

Procedure

1. 1

   Access ABS module
   Locate the ABS hydraulic control unit on the driver side frame rail in the engine compartment, just forward of the master cylinder. Remove any engine covers or air intake components that may obstruct access. On diesel models, the air filter housing may need to be loosened or repositioned for better access.
2. 2

   Disconnect ABS module electrical connector
   Locate the large electrical connector on the ABS module. Press the release tab and carefully disconnect the connector. Inspect the connector terminals for corrosion or damage. If connector is difficult to remove, gently wiggle while pulling - do not force.
3. 3

   Label and photograph brake line connections
   Before removing any lines, take a clear photograph of all brake line connections to the ABS module for reference during reassembly. The number of brake lines connected varies by ABS configuration (typically 4 to 6); verify by inspection. Optionally, label each line with tape indicating its position (front left, rear right, etc.).
4. 4

   Disconnect brake lines from ABS module
   Using appropriate size flare nut wrenches (typically 3/8" and 1/2"), carefully loosen and remove all brake lines (typically 4 to 6, verify by inspection) from the ABS module. Work slowly to avoid rounding off the steel fittings. Immediately cap or plug each line and port on the module to prevent fluid loss and contamination. Place drain pan underneath to catch dripping brake fluid.
   ⚠Use only flare nut wrenches on brake line fittings. Standard open-end wrenches will round off the soft brass fittings.
5. 5

   Remove ABS module mounting fasteners
   Remove the mounting bolts securing the ABS module to the frame rail bracket. Verify the mounting bolt size before starting (commonly 10mm or 13mm on this style bracket). Note the location of any ground wires or brackets attached with these bolts. Support the module while removing the final bolt as it weighs approximately 5-8 pounds when full of fluid.
6. 6

   Remove ABS module from vehicle
   Carefully lift the ABS module assembly out of the engine compartment. Keep the module upright to minimize fluid spillage. Place on a clean work surface covered with absorbent material. Inspect the mounting bracket for damage or excessive corrosion.
7. 7

   Prepare new ABS module
   Unpack the new ABS module and verify it matches the original unit. Check that all ports are properly capped. Remove protective caps only as you install each brake line. Clean the mounting bracket on the vehicle with a wire brush and inspect for any damage.
8. 8

   Install new ABS module
   Position the new ABS module onto the mounting bracket on the frame rail. Thread in the mounting bolts finger-tight, ensuring any ground wires or brackets are properly positioned. Tighten the mounting bolts evenly in a cross pattern. Verify the module is securely mounted and properly aligned with brake line connections.
9. 9

   Connect brake lines to new module
   Remove caps from brake lines and module ports one connection at a time. Thread each brake line fitting into the correct port on the ABS module by hand first to ensure proper thread engagement. Use flare nut wrenches to tighten fittings to the manufacturer-specified torque (typically around 12-18 ft-lbs for brake tube nuts; verify in service manual), being careful not to overtighten. Refer to your photograph to ensure correct line routing.
   ⚠Cross-threading brake line fittings will damage the ABS module. Always start fittings by hand and ensure smooth thread engagement before using wrenches.
10. 10

    Reconnect electrical connector
    Reconnect the electrical connector to the ABS module. Ensure it clicks firmly into place and the locking tab is fully engaged. Gently tug on the connector to verify it is secure.
11. 11

    Refill brake fluid reservoir
    Fill the master cylinder reservoir to the MAX line with fresh DOT 3 brake fluid from a sealed container. Do not reuse old brake fluid.
12. 12

    Bleed brake system conventionally
    Perform conventional brake bleeding in the factory-specified sequence (verify in service manual; commonly right rear, left rear, right front, left front). At each wheel, have an assistant pump the brake pedal 3-4 times and hold pressure while you open the bleeder screw. Close the bleeder before the pedal reaches the floor. Repeat until fluid runs clear with no air bubbles. Keep master cylinder reservoir filled throughout the process.
    ⚠Never allow the master cylinder reservoir to run empty during bleeding or additional air will enter the system.
13. 13

    Perform ABS module bleeding procedure
    Connect an ABS-capable scan tool to the vehicle's diagnostic port. Reconnect the battery negative cable. Turn ignition to ON position (do not start engine). Navigate to the ABS bleeding function in the scan tool. Follow the scan tool prompts to cycle the ABS solenoids and pump motor. This typically involves activating each circuit for 30-60 seconds. Monitor for unusual noises or excessive motor run time which may indicate a problem.
14. 14

    Final brake bleeding
    After completing the ABS scan tool bleeding procedure, repeat the conventional brake bleeding process at all four wheels to purge any air released from the ABS module. Bleed in the factory-specified sequence (verify in service manual). Continue until pedal feels firm and no air bubbles are visible in the discharged fluid.
15. 15

    Clean up and inspect for leaks
    Wipe down all brake line connections and the ABS module with a clean rag. Inspect carefully for any signs of brake fluid leakage at the line fittings. Top off the master cylinder reservoir to the MAX line. Start the engine and verify the ABS warning light illuminates during the bulb check and then goes out after 2-3 seconds.

Reassembly

1. Reinstall any air intake components or engine covers that were removed for access
2. Double-check all brake line connections are tight and leak-free
3. Verify master cylinder reservoir is filled to MAX line with fresh DOT 3 brake fluid
4. Ensure battery negative cable is securely reconnected

Verification

• Start engine and verify ABS warning light goes out after initial bulb check (2-3 seconds)
• With engine running, pump brake pedal several times - it should feel firm and not sink to the floor
• Perform a low-speed test drive in a safe area and verify normal brake operation
• Perform an ABS activation test on a safe surface (gravel or wet pavement) at 15-20 mph to verify ABS system activates properly with pulsing pedal feel
• Re-inspect all brake line connections for leaks after test drive
• Use scan tool to verify no ABS fault codes are present
• Check brake fluid level after test drive and top off if necessary

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