Why Your Lights Flicker on Teslas, Fords and Newer Trucks

Yes. Tesla built a setting for exactly this situation, and most owners don't know it is there. When you plug in an accessory, your Tesla cannot tell a bike rack from a boat trailer — it only sees that something is connected to the lighting circuit — so it engages Trailer Mode by default. Trailer Mode limits Autosteer and related self-driving features, disables rear parking sensor functionality, increases cruise-control following distance, and limits automatic emergency braking force. That is correct behavior for towing a loaded trailer, and unnecessary for a bike rack. THE FIX Turn Trailer Mode off manually while leaving your light plugged in. On the touchscreen go to Controls > Dynamics > Trailer Mode and switch it off. On some software versions the path is Controls > Pedals & Steering > Trailer Mode. The trailer icon on your screen will change to yellow. Tesla's owner's manual defines that yellow icon as the vehicle “detects a connection for trailer lights but Trailer Mode is disabled. It is likely that a carrying accessory has been connected.” That is Tesla telling you it understands you have a rack, not a trailer. WHAT YOU GET IN THAT STATE Your Kody lights continue to work completely normally — running lights, brake lights and turn signals all function. Autosteer and the other Autopilot steering features come back, and cruise control returns to its normal following distance. Rear parking sensors come back too, which means the car may now see your rack as an obstacle. Expect proximity alerts when reversing. Some owners switch Trailer Mode back on for parking, then off again for the highway. Summon is the exception. Tesla's manual notes Summon may not work when a trailer is attached or an accessory is attached, so it will likely stay unavailable with a rack on the hitch either way. ONE THING TO KNOW Trailer Mode may re-engage the next time you start a drive with the light connected, and Tesla does not automatically turn it off when you unplug. It is worth glancing at the trailer icon at the start of a trip. If you are only carrying bikes, you want the yellow accessory icon rather than the active Trailer Mode icon.

It is not just Teslas. This has been documented across brands for years. GENERAL MOTORS GM describes it plainly in its own service documentation for trucks with the trailering app package. GM states that with the ignition off, the trailer lighting control module “will periodically pulse the lighting circuits of the trailer to verify it is still connected,” and that the resulting flashes are “considered normal.” When early trucks pulsed often enough to bother owners, GM's remedy was a software update that reduces the flash to once every 42 minutes when the trailer theft alert is switched off — not a wiring repair, because nothing was broken. FORD Ford owners see it too. An F-150 Lightning owner described his connected trailer's tail lights blinking “a very dim but noticeable pulse every 2s or so” while parked, which other owners identified as a continuity-check heartbeat tied to the truck's trailer theft alert. Gas F-150 owners report a similar dim flicker whenever a trailer is left connected. EUROPEAN BRANDS AND TOYOTA Owners of Land Rover, Porsche, Volkswagen, Mercedes-Benz and Toyota vehicles report similar faint pulsing or flickering when LED trailer lighting is connected. TESLA On Teslas the car is clearly watching that circuit as well. Tesla's Model Y owner's manual states that connecting a trailer's electrical connection while the vehicle is in Park causes the car to engage Trailer Mode automatically, and that the car will alert you if it detects a faulty electrical connection for the trailer lights. Model Y owners with accessory lighting report the same brief, repeating flicker while parked that GM and Ford owners describe. In short: if your vehicle is new enough to have a hitch receiver and a lighting connector, there is a good chance it does some version of this. You are noticing it because Kody's LEDs are efficient enough to show it.

No, on both counts. YOUR LIGHTS The test pulse is a small fraction of the current your Kody light draws in normal operation, and it lasts only a fraction of a second. There is no heat, no stress, and no wear mechanism. LEDs are not consumables the way filament bulbs are — they are not being used up by this. YOUR BATTERY The draw comes from your vehicle's own monitoring circuit, not from your light — the light is simply making visible something that was already happening. Owners of other vehicles who have measured this reported the draw was too small to register on their meter, and that they left accessories connected for days with no trouble starting. If you are storing your vehicle for several weeks, unplugging the connector is a reasonable habit for peace of mind — but that is good practice with any accessory, not something specific to Kody lights.

This is normal, and it is coming from your vehicle — not from the light. Many modern tow-equipped vehicles periodically check their trailer connector to see whether something is plugged in and whether the lamps on it are working. They do this by sending a very brief, very small test current down the lighting circuits — a heartbeat, repeating every few seconds. On a number of vehicles this runs even while parked and switched off, as part of trailer detection and anti-theft monitoring. On old-style incandescent trailer bulbs, that test current is far too weak to make a filament glow, so nobody ever knew it was happening. Kody lights use high-efficiency LEDs that need only a tiny fraction of the power a filament bulb does. Yours are efficient enough to actually respond to the test pulse, so you can see it as a brief flicker. Nothing is wrong, and your light is not malfunctioning. You are seeing something that has always been happening and used to be invisible. If the flicker bothers you when parked at home, unplug the connector. It stops immediately.

Yes — with one important note about sequential (animated) turn signals. Tesla vehicles and some newer Ford models (2016+) can interfere with the sequential turn signal animation due to how their electronics monitor trailer load. The lights will still work — tail lights, brake lights, and turn signals all function correctly. OUR RECOMMENDATION Choose a non-sequential light option for Tesla and newer Fords. You get the same bright tail, brake, and turn signals — just without the animated sweep effect. If you already have a sequential light and are experiencing issues, contact us. We may be able to help with a resistor or other solution.