The 3rd brake light, or center high mount stop lamp (CHMSL), on a 2009 Honda Accord is usually located on the top edge of the trunk lid. Replacing it generally involves accessing the lamp from inside the trunk, disconnecting the wiring, and replacing either the bulb or the entire housing depending on the unit.
While the process is common and repeatable, the exact method depends on whether your CHMSL uses a replaceable bulb or a sealed LED module. This guide walks you through both scenarios, outlining tools, steps, and safety notes to help you complete the repair without unnecessary trips to a shop.
What you’ll need
Gathering the right tools and parts before you start will keep the job smooth. The exact replacement part depends on if your CHMSL uses a bulb or is a sealed LED module.
- Replacement 12-volt bulb (if your CHMSL uses a replaceable bulb)
- Replacement CHMSL assembly (sealed LED module) for non-bulb models
- Phillips screwdriver
- Flat-head screwdriver or plastic trim tool
- Socket wrench with appropriate size (often 8mm or 10mm)
- Trim removal tool or soft cloth to protect surfaces
- Electrical contact cleaner (optional, for connectors)
Having the correct part on hand avoids guesswork and multiple trips. If you’re unsure which type your car uses, check the existing lamp for a replaceable bulb or consult a parts diagram for the 2009 Accord.
Step-by-step replacement
Below are the general steps. If your CHMSL is a sealed LED unit, skip bulb handling and replace the entire assembly as a single piece.
- Open the trunk and locate the CHMSL housing on the inside of the trunk lid. Look for mounting screws or clips securing the light assembly.
- Remove the interior trunk liner or trim panel around the CHMSL to expose the mounting hardware using a trim tool or screwdriver.
- Disconnect the electrical connector from the CHMSL by pressing the release tab and pulling the connector apart. Keep the harness steady to avoid dropping it inside the trunk.
- If you have a bulb-type CHMSL, twist the bulb socket counterclockwise to release it, remove the old bulb, and install a new 12V bulb of the correct size. If the unit is a sealed LED, proceed to step 5 with the entire assembly.
- Remove the light housing from the trunk lid by taking out the mounting screws or unclipping the housing. Be careful not to crack the lens.
- Install the new bulb or the new CHMSL assembly. Reconnect the electrical connector and ensure the housing sits flush against the lid.
- Reinstall the trunk liner, securing any clips or screws. Close the trunk and check the fit.
- Test the brake lights by pressing the brake pedal (engine on or in accessory mode) to confirm the CHMSL lights up. If it doesn’t illuminate, recheck connectors and fuses.
Note: If you find moisture behind the lens or signs of corrosion, consider resealing the housing or replacing any gasket components when you reinstall the CHMSL.
Summary
Replacing the 3rd brake light on a 2009 Honda Accord is a straightforward maintenance task. Determine whether your CHMSL uses a bulb or a sealed LED module, assemble the right tools and replacement part, and carefully access, disconnect, and swap the lamp. Reassemble, test, and inspect for leaks to complete the repair successfully. If you’re uncertain or uncomfortable with the process, consulting a professional is advisable.