Remove and replace the ABS (Anti-lock Braking System) module on a 2023 Chevrolet Bolt EUV, including brake system bleeding and electrical reconnection.

Warnings

Tools required

Parts

• ABS Control Module Assembly × 1 — Use OEM GM part number for 2023 Bolt EUV
• Brake line sealing washers × 4 — GM copper washers for brake lines

Fluids

• ACDelco DOT 4 Brake Fluid — 1 qt

Preparation

1. Park vehicle on level ground and engage parking brake
2. Turn off vehicle and remove key fob from vehicle interior
3. Open hood and support with prop rod
4. Disconnect negative (-) terminal of 12V battery located in rear cargo area (remove cargo floor panel to access)
5. Wait minimum 5 minutes for all electrical systems to discharge
6. Place clean drain pan under ABS module area to catch brake fluid
7. Ensure you have a sealed container of fresh ACDelco DOT 4 brake fluid
8. Remove engine cover if equipped for better access
9. Photograph or document all electrical connector orientations and brake line positions for reassembly

Procedure

1. 1

   Remove ABS module electrical connector
   Locate the ABS module on the driver's side of the engine bay near the brake master cylinder. Identify the large multi-pin electrical connector on the module. Press the locking tab and carefully disconnect the electrical connector. Inspect connector pins for corrosion or damage.
2. 2

   Label and disconnect brake lines
   Identify all brake lines connected to the ABS module (typically 4-6 lines). Using tape or labels, mark each brake line and corresponding port on the module for correct reassembly. Clean the area around each fitting with brake cleaner to prevent contamination. Using a flare nut wrench, carefully loosen each brake line fitting. Expect significant brake fluid spillage - keep drain pan positioned underneath.
   ⚠Use only flare nut wrenches to prevent rounding off brake line fittings. Standard wrenches will damage the soft brass fittings.
   Torque spec

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

   Remove ABS module mounting bolts
   Locate the ABS module mounting bolts securing the module to its bracket (typically 2-3 bolts). Using appropriate socket, remove all ABS module mounting bolts. Support the module with one hand while removing the final bolt to prevent it from falling.
   Torque spec

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

   Remove ABS module from vehicle
   Carefully lift the ABS module assembly away from the mounting bracket. Keep the module upright to minimize brake fluid spillage. Place the old module in a safe location away from work area. Inspect the mounting bracket for damage or corrosion.
5. 5

   Inspect and clean mounting area
   Thoroughly clean the mounting bracket and surrounding area with brake cleaner. Remove any corrosion, debris, or old brake fluid residue. Inspect mounting bolt holes for thread damage. Verify all brake line ports are clean and free of debris before installing new module.
6. 6

   Install new ABS module
   Remove the new ABS module from packaging. Verify part number matches original module. Position the new module onto the mounting bracket, aligning all mounting bolt holes. Install ABS module mounting bolts finger-tight initially to ensure proper alignment.
   Torque spec

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

   Torque ABS module bolts
   Using a calibrated torque wrench, tighten each ABS module mounting bolt to specification in a cross pattern to ensure even seating. Verify module is securely mounted with no movement.
   ⚠CRITICAL TORQUE: Over-tightening can crack the module housing. Under-tightening can allow movement during ABS events. Use precise torque wrench.
   Torque spec

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

   Connect brake lines to new module
   Install new copper sealing washers on each brake line fitting. Thread each brake line fitting into the correct port on the ABS module (use labels from disassembly). Start all fittings by hand to prevent cross-threading. Once all fittings are hand-tight, use a line wrench or flare nut wrench to tighten each fitting to specification. Tighten in sequence from center ports outward.
   ⚠️CRITICAL: Cross-threaded brake lines will leak and cause brake failure. If any fitting does not thread smoothly by hand, stop and investigate. Never force fittings.
   Torque spec

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

   Reconnect electrical connector
   Inspect the electrical connector on the wiring harness for any corrosion or damaged pins. Align the connector with the ABS module connector and press firmly until you hear and feel the locking tab engage. Gently tug on the connector to verify it is fully locked.
10. 10

    Reconnect 12V battery
    Return to rear cargo area and reconnect the negative (-) terminal of the 12V battery. Ensure connection is tight and secure. The vehicle systems will initialize - this is normal.
11. 11

    Fill brake fluid reservoir
    Locate the brake fluid reservoir near the master cylinder. Check fluid level and fill to the MAX line using only fresh ACDelco DOT 4 brake fluid from a sealed container. Do not overfill.
    ⚠Use only DOT 4 brake fluid. Never mix different brake fluid types or use contaminated fluid.
12. 12

    Perform manual brake bleeding
    Starting with the wheel furthest from the ABS module (typically right rear), attach clear tubing to the bleeder screw and submerge the other end in clean brake fluid in a container. Have an assistant pump the brake pedal 3-5 times and hold pressure. Open the bleeder screw briefly to release fluid and air, then close before pedal reaches floor. Repeat until fluid flows clear without air bubbles. Move to left rear, right front, then left front wheel. Continuously monitor and refill reservoir - never let it run dry.
    ⚠️If brake reservoir runs dry during bleeding, air will enter the system requiring complete re-bleeding. Check level after each wheel.
    Torque spec

    Bleeder Screw14 Nm (10 lb-ft)
13. 13

    Perform ABS automated bleeding with scan tool
    Connect GDS2 or equivalent GM-compatible professional scan tool to the vehicle's OBD-II port. Navigate to ABS system and select 'Automated Bleeding' function. Follow on-screen prompts to cycle ABS solenoids while manually bleeding each wheel as directed by the scan tool. This is essential to remove air from ABS valve body.
    ⚠️CRITICAL: Manual bleeding alone is insufficient for ABS modules. Automated bleeding with scan tool is mandatory to purge air from internal valves. Skipping this step will result in brake failure during ABS activation.
14. 14

    Program and calibrate ABS module
    Using the GDS2 scan tool, perform ABS module programming to match vehicle VIN and configuration. Follow all on-screen prompts for module setup and calibration. Perform any required steering angle sensor calibration if prompted. Clear all diagnostic codes and verify no active ABS faults are present.
    ⚠️The ABS module MUST be programmed to this specific vehicle. An unprogrammed module will not function correctly and may cause brake system malfunction.
15. 15

    Final brake system inspection
    With engine off, pump brake pedal firmly 20-30 times. Pedal should become firm and maintain height. Inspect all brake line fittings at the ABS module for any signs of leakage. Wipe fittings dry and check again. Start vehicle and verify ABS warning light illuminates briefly then extinguishes. Check brake fluid level and top off to MAX line if needed.

Reassembly

1. Reinstall engine cover if removed
2. Clean any spilled brake fluid from engine bay components and painted surfaces immediately
3. Double-check all brake line fittings are torqued to specification with no leaks
4. Verify brake fluid reservoir is at MAX level with fresh DOT 4 fluid
5. Ensure all tools and parts packaging are removed from engine bay

Verification

• Start vehicle and verify ABS warning light illuminates for 2-3 seconds then turns off. If light stays on, there is a fault requiring diagnosis
• With vehicle running, press brake pedal firmly - it should be high and firm with no sponginess or excessive travel
• Perform a low-speed brake test in a safe area (under 10 mph) to verify normal brake function
• Perform a controlled ABS activation test in a safe area (wet pavement or gravel at 20-25 mph) to verify ABS pulses properly - you should feel pedal pulsation and hear ABS pump operation
• Re-check all brake line fittings for leaks after test drive - any wetness indicates a leak
• Scan for diagnostic trouble codes using scan tool - there should be no active ABS codes
• Verify brake fluid level has not dropped - a drop indicates a leak in the system
• Test drive vehicle at various speeds with hard braking to confirm full brake system function before returning to service
• If ANY abnormality is detected (warning lights, soft pedal, leaks, unusual noises), DO NOT DRIVE THE VEHICLE and seek professional assistance immediately

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