Third Brake Light

Remove and replace the third brake light (center high-mounted stop lamp) on a 1992 Dodge Viper RT/10, including lens/housing removal and bulb/circuit verification.

Warnings

Tools required

Parts

• Third brake light assembly (center high-mounted stop lamp) × 1 — Mopar 4740636 or equivalent
• Replacement bulb (921/194 wedge base) × 1 — Standard 921 or 194 bulb

Preparation

1. Park vehicle on level surface and engage parking brake
2. Turn ignition off and remove key
3. Disconnect negative battery terminal and wait 2 minutes for airbag system capacitors to discharge
4. If recently driven, allow brake light housing to cool (bulb operates at high temperature)
5. Clean surrounding area to prevent dirt intrusion into lamp housing

Procedure

1. 1

   Access third brake light housing
   From exterior rear of vehicle, locate the center high-mounted stop lamp assembly on the rear deck panel behind the cockpit. The RT/10 CHMSL location and mounting method should be verified against the factory service manual for this specific vehicle, as the 1992 open roadster does not have a conventional rear deck lid or fixed rear panel. Inspect the perimeter of the lens for visible fastener access points or trim clips.
2. 2

   Remove lens/housing fasteners
   Remove the Phillips screws securing the third brake light lens or housing assembly. The fastener count and retention method (screw, clip, or adhesive) for the 1992 RT/10 CHMSL must be confirmed against the factory service manual before proceeding, as this varies and is not verified. Retain fasteners for reinstallation. If lens is adhesive-mounted rather than screw-retained, gently work a flat-blade trim tool around perimeter to break adhesive seal, working slowly to avoid cracking lens.
3. 3

   Disconnect electrical connector
   Carefully pull the third brake light housing away from the mounting surface to expose the rear wiring harness. Locate the electrical connector attached to the lamp socket. Depress the locking tab (if present) and pull connector straight off the socket terminals. Do not pull on wires; grasp connector body only.
4. 4

   Remove third brake light assembly
   With connector disconnected, fully remove the third brake light housing and lens assembly from the vehicle. Set aside on clean work surface. Inspect mounting area for dirt, moisture intrusion, or corrosion.
5. 5

   Inspect and test bulb
   Remove bulb from socket by pulling straight out (921/194 wedge-base bulb design). Visually inspect bulb filament for breakage. Use test light or multimeter to verify socket receives power: reconnect battery negative terminal temporarily, turn ignition on, and have assistant depress brake pedal while you probe socket terminals. Should read 12V DC at socket when brake pedal is depressed. Disconnect battery negative terminal again before proceeding.
6. 6

   Clean lens and housing
   Clean interior and exterior surfaces of lens and housing with lint-free cloth. Remove any moisture, dirt, or oxidation from socket contacts and housing mounting surface. Inspect lens for cracks or UV degradation; replace if compromised.
7. 7

   Install new or tested bulb
   Insert new or verified-working bulb into socket, pressing firmly until wedge base seats completely. Ensure bulb is fully inserted and makes positive contact with socket terminals.
8. 8

   Reconnect electrical connector
   Align electrical connector with socket terminals and press firmly until locking tab clicks (if equipped). Gently tug connector to verify secure connection. Do not force; connector should mate with light resistance.
9. 9

   Position housing and secure fasteners
   Position third brake light housing into mounting location, ensuring any alignment pins or gasket material seats properly. If adhesive-mounted, apply new automotive-grade adhesive sealant per manufacturer instructions before seating. If screw-retained, align screw holes and install the 2 Phillips screws, tightening evenly in alternating pattern to avoid cocking housing. Do not overtighten plastic housing threads.
10. 10

    Reconnect battery and test operation
    Reconnect negative battery terminal. Turn ignition to ON position (engine off). Have assistant depress brake pedal while you observe third brake light from rear of vehicle. Lamp should illuminate brightly and immediately. Cycle brake pedal several times to confirm consistent operation. Verify other brake lights still function normally.

Reassembly

1. Installation is reverse of removal with attention to connector locking tabs and fastener torque
2. Ensure housing gasket or seal (if present) is properly seated to prevent moisture intrusion
3. If adhesive-mounted, allow adhesive to cure per manufacturer specifications before driving

Verification

• Third brake light illuminates brightly and consistently when brake pedal is depressed
• Light extinguishes completely when brake pedal is released
• No flickering or intermittent operation observed
• Lens is secure with no gaps or misalignment
• All other brake lights continue to function normally
• No water leaks around housing after car wash or rain

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