Replace the third brake light (center high-mounted stop lamp) on the rear tailgate of a 2012-2018 Jeep Wrangler JK.

Warnings

Tools required

Parts

• Third brake light assembly (CHMSL) × 1 — 55157398AB or equivalent
• Replacement bulb (if reusing assembly) × 1 — 921 wedge bulb or LED assembly as equipped

Preparation

1. Park vehicle on level surface and engage parking brake
2. Turn ignition to OFF position
3. If replacing entire assembly, disconnect negative battery terminal and wait 2 minutes
4. Open rear tailgate fully and ensure it is securely supported
5. Clean area around third brake light to prevent debris from entering tailgate cavity

Procedure

1. 1

   Access third brake light assembly
   Open the rear tailgate. The third brake light is mounted on the exterior upper edge of the tailgate. Identify the two Torx T15 screws securing the assembly to the tailgate on either side of the light housing. These screws are accessible from the exterior.
2. 2

   Remove mounting screws
   Using a Torx T15 driver, remove both mounting screws from the third brake light assembly. Support the light assembly with one hand while removing the second screw to prevent it from falling. Set screws aside in a secure location.
3. 3

   Separate light assembly from tailgate
   Gently pull the third brake light assembly away from the tailgate. It may be secured with clips or weatherstrip adhesive, so apply steady, even pressure. If resistance is encountered, use a trim removal tool to gently pry around the edges, working slowly to avoid breaking mounting tabs.
4. 4

   Disconnect electrical connector
   Once the assembly is loose, locate the electrical connector on the back of the light assembly. Press the release tab on the connector and pull straight back to disconnect the wiring harness from the brake light assembly. For hardtop models, you may need to reach through the tailgate opening to access the connector. Note the orientation of the connector for reassembly.
   ⚠Do not pull on wires themselves; only pull on the connector body to avoid damaging the wiring harness.
5. 5

   Replace bulb or entire assembly
   If replacing only the bulb, twist the bulb socket counterclockwise approximately 1/4 turn and remove from the assembly. Pull the wedge-style bulb straight out of the socket. Insert new bulb into socket, ensuring it seats fully. Reinstall socket into assembly by aligning tabs and twisting clockwise until it locks. If replacing the entire assembly, proceed with the new complete unit.
6. 6

   Reconnect electrical connector
   Align the electrical connector with the socket on the new or refurbished brake light assembly. Push firmly until you hear and feel a positive click, indicating the locking tab has engaged. Gently tug on the connection to verify it is secure.
7. 7

   Test brake light function
   Before final installation, have an assistant press the brake pedal while you verify the third brake light illuminates properly. If battery was disconnected, temporarily reconnect it for this test. Check for full, even illumination across the entire light assembly. If light does not function, verify connector engagement and bulb installation.
   ⚠️Do NOT proceed with final installation if the brake light does not illuminate. A non-functional third brake light creates serious collision risk and violates federal motor vehicle safety standards.
8. 8

   Install assembly to tailgate
   Position the third brake light assembly onto the tailgate, ensuring the electrical connector has adequate slack and is not pinched. Align the mounting screw holes with the corresponding holes in the tailgate. Verify that any weatherstrip gasket is properly positioned around the perimeter of the light.
9. 9

   Install and torque mounting screws
   Start both Torx T15 mounting screws by hand to ensure proper thread engagement. Using a torque wrench, tighten the mounting screws to 12.0 Nm (9.0 lb-ft) in an alternating pattern (tighten one screw partially, then the other, then return to final torque). Do not overtighten as this can crack the plastic housing or damage the tailgate.
   Torque spec

   Cover Screws12 Nm (9 lb-ft)
10. 10

    Reconnect battery if disconnected
    If the negative battery terminal was disconnected, reconnect it now. Clean both the terminal post and cable clamp with a wire brush if corrosion is present. Place the negative cable onto the negative terminal post and tighten the terminal bolt to 8.0 Nm (6.0 lb-ft).
    Torque spec

    Battery Terminal Bolts8 Nm (6 lb-ft)

Reassembly

1. Ensure weatherstrip seal is properly seated around entire perimeter of light assembly to prevent water intrusion
2. Verify no wiring is pinched between light assembly and tailgate body
3. Check that both mounting screws are tight and the assembly does not move when pressed firmly

Verification

• With engine off and ignition in ON position, have an assistant press and release the brake pedal multiple times while you observe the third brake light from behind the vehicle
• Verify the third brake light illuminates immediately when brake pedal is pressed and extinguishes when released
• Confirm the light illuminates evenly across the entire lens with no dark spots or flickering
• Check for proper sealing by inspecting for gaps between the light assembly and tailgate
• Test brake lights again after closing tailgate to ensure wiring was not damaged during tailgate operation
• Perform a brief test drive and verify all brake lights function normally under actual driving conditions

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