In this tech article I will show you how to replace the third brake light lens assembly and spoiler on your BMW X3. The third brake (high mount) light is made of multiple LED lights and is serviced as a complete unit. The lens on the third brake light wears and becomes dull over time or cracks. I find replacing it improves the look of the vehicle and visibility of the light. If you have a water leak in your rear hatch, check that the lens and spoiler is sealed well and it is not the source of the water leak. Also inspect the tail light for water leaks.
When dealing with repeated bulb failure, inspect the electrical connector and bulb holder. The connectors can wear over time causing heat and melting. Once the electrical connector on the harness side or the bulb socket has melted, you will have a poor connection and bulb faults or failures. If you find the connector is melted, you can repair it by installing a new plug pigtail and / or replacing the bulb socket assembly.
To avoid marring the trim or paint if you need to pry anything, work with a plastic prying tool or wrap a screwdriver tip with masking tape before prying.
Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.
Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.
Vehicle models change and evolve as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.
The third brake light (red arrow) on X3 models is mounted in the spoiler (blue arrow).
Start by removing the tail gate trim panel. See our tech article on tail gate trim panel replacing. Then disconnect the module electrical connector (yellow arrow) by pulling it straight out. Next use a trim panel tool to remove the module harness mount (green arrow). Remove the three plastic caps by pulling them straight out, then remove the three 10mm nuts beneath them. Remove the four remaining 10mm nuts (blue arrows) from the rear spoiler. Support the spoiler as you remove the final but.
Use a small pick and open the grommet boot enough to allow the harness (red arrow) from the module to be pulled through slightly. This allows for enough movement in the harness to flip the spoiler over to access the third brake light fasteners.
Flip the spoiler back over and pull the third brake light straight out to remove (red arrow). Thoroughly clean the tail gate and lens mating surface. If there is any wear touch it up to prevent rust. Once you prepare the mating surface, install the new lens. Check the operation of the light when complete. If you need to remove the spoiler completely, pull the harness through the grommet and remove the spoiler.