As Tesla continues to expand the utility of its vehicles, a recent update to the official mobile app has revealed a hidden feature that will soon make towing easier. In app version 4.55.5, Tesla added a new text string pointing to an upcoming capability that will allow owners to test their trailer lights directly from their smartphones.
Solving a Common Towing Headache
Anyone who frequently tows a boat, camper, or utility trailer knows the frustration of the pre-trip light check. To ensure that the trailer's brake lights, running lights, and turn signals are properly synced with the tow vehicle is a safety and legal requirement.
Historically, this has been a two-person job: one person sits in the driver's seat pressing the brake pedal and activating the blinkers, while the other stands behind the trailer to confirm everything is illuminated correctly.
For solo drivers, the task becomes more difficult. The process can involve the driver only checking some features, like turn signals, or more awkward setups, like propping up a phone camera to check that all their trailer lights are working properly.
By integrating a trailer light test directly into the Tesla app, owners would be able to quickly and easily test their trailer lights by standing behind their trailer with their Tesla app.
This feature likely stems from the Tesla Semi, which already includes various testing features for owners to check their truck prior to a trip.
The Code Hint
The upcoming feature was discovered by digging through the source code of the Tesla app version 4.55.5. There was a phrase in the app called MOBILE_APP_FEATURE_TRAILER_LIGHT_TEST , as found by @Tesla_App_iOS.
Tesla frequently updates its mobile app to lay the groundwork for future vehicle features. These backend code strings are reliable indicators of what the engineering team is preparing to launch or is at least testing in the real world.
Coming to the Vehicle UI
While a dedicated trailer light testing mode isn’t available yet in Tow Mode, we imagine that this new string entry means that Tesla will eventually bring the feature to the vehicle UI as well.
With the Cybertruck expanding Tesla's market into the heavy-duty towing segment, and with the already capable Model X and Model Y, adding quality-of-life towing features is a logical next step for the software team.
