Electronic Parking Brake Motor

This procedure covers the replacement of the electronic parking brake motor/actuator on the rear brake caliper assembly of a 2023 Chevrolet Bolt EUV.

Warnings

Tools required

Parts

• Electronic parking brake motor/actuator × 1 — Use OEM specification
• EPB motor seal/O-ring (if not included with motor) × 1 — Use OEM specification

Preparation

1. Park vehicle on a level, firm surface and ensure the transmission is in Park
2. Place wheel chocks in front of the front wheels
3. Disconnect the negative terminal of the 12-volt battery (located in rear cargo area) and wait at least 2 minutes for system capacitors to discharge
4. Loosen the rear wheel lug nuts while vehicle is on the ground, but do not remove
5. Raise the rear of the vehicle using a floor jack and support securely on jack stands rated for the vehicle weight
6. Remove the rear wheel completely
7. Clean the caliper area with brake cleaner to remove dirt and debris

Procedure

1. 1

   Retract electronic parking brake using scan tool
   Reconnect the 12V battery temporarily. Connect an appropriate scan tool capable of EPB service functions. Navigate to the EPB service menu and select 'Retract EPB Caliper' or 'Service Mode'. Follow the scan tool prompts to fully retract the EPB motor and place the system in service mode. This moves the caliper piston to the fully retracted position. Once complete, disconnect the 12V battery again for safety.
   ⚠️Do not attempt to manually compress the EPB caliper piston without using the scan tool retract function first. The integrated electric motor prevents manual compression and forcing it will damage the caliper assembly.
2. 2

   Disconnect EPB motor electrical connector
   Locate the electrical connector on the EPB motor assembly at the rear of the caliper. Press the release tab and carefully disconnect the wiring harness connector from the EPB motor. Inspect the connector terminals for corrosion or damage.
3. 3

   Remove EPB motor mounting bolts
   Identify the EPB motor mounting bolts (typically 2 bolts) securing the motor to the rear brake caliper body. Using the appropriate socket, remove the mounting bolts completely. Keep these bolts if they are in good condition and do not require replacement per service manual specifications.
   ⚠Support the EPB motor as you remove the final bolt to prevent it from falling and damaging the motor gear mechanism or connector pins.
   Torque spec

   Mounting Bolts27 Nm (20 lb-ft)
4. 4

   Remove EPB motor from caliper
   Carefully pull the EPB motor assembly straight out from the caliper body. There may be a seal or O-ring on the motor shaft that should come out with the motor. If the motor is stuck, gently rotate it while pulling to break the seal. Do not pry against the caliper body as this can damage sealing surfaces.
5. 5

   Inspect caliper mounting surface and clean
   Inspect the EPB motor mounting area on the caliper for corrosion, debris, or damage to the sealing surface. Use a wire brush to clean the mounting surface and bolt holes. Inspect the threaded holes for damage. Check the caliper piston mechanism for proper operation by visually confirming it is fully retracted.
6. 6

   Prepare new EPB motor for installation
   Remove the new EPB motor from its packaging. Verify it matches the original part configuration. Install a new seal or O-ring onto the motor shaft if one is provided separately (some motors come with the seal pre-installed). Lightly lubricate the seal with clean brake fluid to ease installation. Ensure the motor gear is in the retracted/service position.
7. 7

   Install new EPB motor
   Align the EPB motor with the mounting holes on the caliper body. Ensure the motor shaft engages properly with the caliper piston mechanism. Push the motor straight into the caliper body until it seats flush against the mounting surface. Verify the seal is not pinched or damaged during installation.
   ⚠Ensure the motor shaft aligns with the caliper piston gear before forcing the motor into position. Misalignment can damage both components.
8. 8

   Install and torque EPB motor mounting bolts
   Insert the EPB motor mounting bolts and thread them by hand to ensure proper thread engagement. Tighten the bolts in a cross pattern (if applicable) to ensure even seating. Torque the mounting bolts to specification using a calibrated torque wrench.
   Torque spec

   Mounting Bolts27 Nm (20 lb-ft)
9. 9

   Reconnect EPB motor electrical connector
   Reconnect the wiring harness connector to the new EPB motor. Ensure the connector locks fully into place with an audible click. Gently tug on the connector to verify it is secure. Route the wiring away from any moving parts or heat sources.
10. 10

    Exit EPB service mode and test motor operation
    Reconnect the 12V battery. Connect the scan tool and navigate to the EPB service menu. Select 'Exit Service Mode' or 'Apply EPB'. The scan tool will command the EPB motor to cycle and perform a self-calibration. Listen for smooth motor operation without unusual grinding or clicking noises. The scan tool should confirm successful calibration. If errors occur, verify all connections and repeat the procedure.
    ⚠Keep hands and tools clear of the caliper during EPB motor cycling. The motor will apply force to the brake pads and can cause pinching injuries.
11. 11

    Reinstall wheel and lower vehicle
    Reinstall the rear wheel onto the hub. Thread all lug nuts by hand to prevent cross-threading. Tighten the lug nuts in a star pattern using a torque wrench to the specified torque value. Lower the vehicle from the jack stands and remove the stands. Lower the vehicle completely to the ground. Perform a final torque check on the lug nuts with the vehicle on the ground.
    Torque spec

    Wheel Lug Nuts136 Nm (100 lb-ft)

Reassembly

1. Ensure all electrical connections are secure and properly routed
2. Verify the EPB motor mounting bolts are torqued to specification and the motor is seated flush against the caliper
3. Disconnect the scan tool and secure the 12V battery negative terminal connection

Verification

• With the engine off, press the electronic parking brake button to apply the parking brake. You should hear the EPB motors engage and feel resistance if you attempt to push the vehicle
• Release the parking brake using the button and verify the brake releases (no motor noise indicates release)
• Start the vehicle and test the parking brake apply/release function multiple times to confirm proper operation
• Perform a low-speed parking lot test to verify normal service brake operation is not affected
• Check for any warning lights on the instrument cluster related to the brake system or parking brake
• Verify no unusual noises come from the rear brakes during light brake applications
• Use the scan tool to check for any stored diagnostic trouble codes related to the EPB system. Clear codes if the repair resolved the original fault

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

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