This procedure covers the removal and replacement of the center high-mounted stop lamp (third brake light) on the 2023 Chevrolet Bolt EUV, a safety-critical brake signaling component.

Warnings

Tools required

Parts

• Center high-mounted stop lamp assembly × 1 — GM 84954549 or equivalent
• Trim panel retaining clips (if damaged) × 4 — Use OEM specification

Preparation

1. Park vehicle on level surface and engage parking brake
2. Turn ignition off and remove key fob from vehicle interior
3. Open rear liftgate fully and secure in open position
4. Allow interior to warm to room temperature if vehicle has been in freezing conditions
5. Disconnect 12V auxiliary battery negative terminal (located in front trunk area) and wait 2 minutes to allow capacitors to discharge
6. Gather all tools and replacement parts before beginning work
7. Photograph existing wiring connections before disconnection for reference

Procedure

1. 1

   Access Third Brake Light Assembly
   From inside the cargo area with liftgate open, locate the third brake light housing mounted in the upper center of the liftgate trim panel. Identify the access point behind the upper trim panel where the light assembly is mounted.
2. 2

   Remove Upper Liftgate Trim Panel
   Using trim panel removal tools, carefully release the retaining clips securing the upper liftgate trim panel. Start from one end and work across, gently prying the panel away from the liftgate structure. There are typically 4-6 push-pin style clips. Pull the panel forward to disengage it completely and set aside in a safe location.
   ⚠Apply even pressure when releasing clips. Forcing or prying at wrong angles will break the clips or crack the trim panel.
3. 3

   Disconnect Electrical Connector
   Locate the electrical connector attached to the back of the third brake light assembly. Press the locking tab and carefully pull the connector straight out from the lamp assembly. Do not pull on the wires themselves. If connector is difficult to remove, use electrical contact cleaner on the connector and verify the locking tab is fully released.
   ⚠Do not force the electrical connector. Broken connector tabs will require replacement of the entire wiring harness.
4. 4

   Remove Lamp Assembly Mounting Fasteners
   Using a T20 Torx driver, remove the mounting screws securing the third brake light assembly to the liftgate. There are typically 2-3 screws. Keep all fasteners organized for reinstallation. Note the position of any spacers or grommets.
   ℹ️Some fasteners may have thread-locking compound applied from the factory. Apply steady pressure to break loose.
5. 5

   Remove Third Brake Light Assembly
   Carefully pull the third brake light assembly away from the liftgate. The unit may have rubber seals or gaskets that create resistance. Wiggle gently while pulling straight out to avoid damaging the mounting points. Inspect the gasket for damage and replace if torn or compressed.
6. 6

   Inspect Mounting Area and Clean Contact Points
   Inspect the mounting surface on the liftgate for corrosion, damage, or water intrusion. Clean the mounting area with a lint-free cloth. Check that the gasket sealing surface is clean and dry. Inspect the electrical connector pins in the vehicle harness for corrosion or damage. Clean connector contacts with electrical contact cleaner if needed.
7. 7

   Test New Lamp Assembly (Pre-Installation Verification)
   Before installation, reconnect the 12V battery negative terminal temporarily. With the new lamp assembly connected to the vehicle harness (but not mounted), have an assistant activate the brake pedal while you verify all LED segments illuminate properly. Disconnect battery again after verification.
   ⚠️This pre-installation test is CRITICAL. Installing a defective lamp creates immediate safety hazard. Verify 100% LED function before proceeding.
   Torque spec

   Battery Terminal Bolts6 Nm (4 lb-ft)
8. 8

   Install New Third Brake Light Assembly
   Position the new lamp assembly into the liftgate opening, ensuring any gasket or seal is properly seated. Align the mounting holes with the liftgate structure. Verify the assembly sits flush against the mounting surface with no gaps that could allow water intrusion.
9. 9

   Install Mounting Fasteners
   Install the T20 Torx mounting screws finger-tight first to ensure proper alignment. Then tighten screws in an alternating pattern to ensure even seating of the assembly. Do not overtighten as this can crack the lamp housing or compress gaskets excessively. Torque to snug plus 1/8 turn (approximately 3-4 Nm).
10. 10

    Connect Electrical Connector
    Align the electrical connector with the lamp assembly terminals and push firmly until the locking tab clicks into place. Gently tug on the connector to verify it is fully seated and locked. Ensure no wires are pinched or under tension.
11. 11

    Reinstall Upper Liftgate Trim Panel
    Position the upper trim panel into place, aligning all mounting points. Press firmly on each clip location until you hear/feel the clips snap into place. Verify the panel sits flush and all gaps are even around the perimeter. Replace any broken clips identified during removal.
12. 12

    Reconnect 12V Battery and Clear Codes
    Reconnect the 12V auxiliary battery negative terminal in the front trunk area. Verify the terminal is clean and tight. If available, use a scan tool to clear any diagnostic trouble codes generated by the battery disconnection.
    ℹ️Vehicle may require window auto-up/down relearn procedure after battery reconnection. Consult owner's manual for your specific vehicle.
    Torque spec

    Battery Terminal Bolts6 Nm (4 lb-ft)

Reassembly

1. Ensure all trim panels are fully seated with no gaps or misalignment
2. Verify liftgate closes and latches properly without interference from new lamp assembly
3. Check that no tools or parts were left in the liftgate cavity
4. Reset clock, radio presets, and other settings affected by battery disconnection

Verification

• With vehicle running and an assistant operating the brake pedal, verify the third brake light illuminates fully and brightly with all LED segments functioning
• Test third brake light function with headlight switch in all positions (off, parking lights, headlights on) to ensure it operates independently
• Perform brake light test with liftgate both open and closed to verify no wiring interference
• Inspect lamp assembly from outside vehicle to verify proper seating, no gaps, and professional appearance
• Close and open liftgate multiple times to ensure no interference with lamp assembly or wiring
• If available, use scan tool to verify no brake light system fault codes are present
• Perform a test drive and have another vehicle follow to confirm third brake light is visible and functioning during actual braking
• Document repair completion and advise vehicle owner to monitor third brake light function for first few days of operation

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