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Replacing an RV tail light involves disconnecting power, removing the old fixture, connecting a compatible replacement, testing its functions, and sealing it against moisture. The key is to match the correct light and wiring connections while protecting the rear wall from damage. These five steps follow the replacement process demonstrated by Keystone’s Matt and Bart for a surface-mounted trailer tail light.
A light that stops working does not always need a complete replacement. A loose connection, damaged wiring, poor ground, or failed replaceable bulb may be responsible. Check these possibilities before ordering a new assembly.
If the fixture needs replacement, confirm that the new light matches its mounting style, dimensions, electrical connections, and lighting functions. Some assemblies also illuminate the license plate or support its mounting bracket. Make sure the replacement includes those features if needed.
The steps below apply to the style of light shown in the demonstration. Follow your replacement light’s instructions if its mounting or wiring differs.
Before starting, have the replacement light and these supplies ready:
Use connectors approved for the wire size and installation conditions. Follow the connector manufacturer’s instructions rather than relying on electrical tape to hold a connection together.
Unplug the 7-way connector from the tow vehicle to disconnect the truck’s power supply to the trailer lights. Follow your RV’s wiring information and the replacement light’s instructions to isolate any additional supply to the circuit. Verify that the wiring is not energized before cutting or stripping wires.
Remove the lens cover as directed for your light assembly. Some sealed lights do not have a separately removable lens.
Support the fixture while removing its mounting screws. Carefully score the old sealant around the base, keeping the blade away from wiring and avoiding cuts into the RV’s exterior finish. Gently separate the base from the rear wall without straining the wires.
Pull out only enough wiring to access the connections. Before disconnecting anything, take a clear photo and label the wires by function so you can identify them during installation.
If the light uses a removable plug, disconnect it. For a hardwired assembly, cut the wires only after confirming power is off, leaving enough RV-side wire for the new connections.
Remove the old putty tape and sealant from the mounting area. Use a compatible adhesive remover and cleaner according to their instructions, then let the surface dry. If you find soft wall material, damaged wiring, or signs of water intrusion, have the problem evaluated before installing the new light.
Apply butyl or putty tape to the back of the replacement light where specified by the installation instructions.
Strip the RV wires and replacement light leads to the length required by the connectors. The original demonstration uses approximately ½ inch, but the connector’s specified strip length takes priority.
Connect each wire by function, using your labels, photo, and the replacement light’s wiring diagram. Do not assume wire colors match between the old and new assemblies.
Secure the connections with properly sized connectors. If using crimp-style bell caps, crimp them with the specified tool and gently check that each wire is secure. Make sure no bare conductor remains exposed.
With the connections insulated and the fixture safely supported, reconnect the 7-way connector to the tow vehicle.
Have a helper operate the controls while you check the replacement assembly’s functions:
If a function does not work, disconnect power before inspecting the wiring again. Check the connections and ground rather than assuming the new fixture is defective.
Once testing is complete, disconnect the 7-way connector again before finishing the installation.
Carefully tuck the wiring into the opening without pinching or straining it. Position the base and reinstall the mounting screws, tightening them evenly without cracking the housing or stripping the holes.
Reinstall the lens cover if applicable. Apply compatible sealant where the fixture meets the rear wall, following the light and sealant manufacturers’ instructions. Keep any designated drain openings clear.
Follow the sealant’s curing instructions, then reconnect the 7-way cord and perform a final lighting check.
Explore Keystone’s DIY repair resources for more RV maintenance guidance.
Disclaimer: The information contained in this article is deemed to be true and accurate at the time of publication. However, due to the evolving nature of our products and services, there may be changes or updates that occur after this article was published. We encourage users to verify the contents and consult with their dealer or Keystone RV for the most current information. If you have any questions or require further clarification, please do not hesitate to contact your dealer or reach out to Keystone RV directly.