“Call the holy mechanic.”
The key is out of the ignition. The engine is off. Then a mechanic flips the headlight switch, and the Cadillac answers by lighting up its dashboard and starting itself. No push-button or spare key—just a car that appears to ignore the rules of reality.
The startling clip from TikToker Alex Rodrigues (@arodrigues78) shows him holding up the key, more than a foot away from the ignition. But when he flips on the vehicle’s headlights, the circuitry starts acting on its own.
Rodrigues and an off-camera friend try to stifle their laughter and disbelief in the viral video, which has been viewed more than 242,000 times.
As the video made the rounds, viewers rushed to the comments section with a familiar mix of humor and horror. Some joked that the Cadillac was “possessed,” while others suggested calling a priest or invoking Stephen King’s novel Christine.”A few longtime General Motors owners weren’t surprised at all, blaming the brand’s reputation for electrical gremlins.
But beneath the jokes, a more serious conversation emerged among technicians and experienced DIYers. Several commenters zeroed in on the same likely explanation: an aftermarket remote start or alarm module that had failed internally and begun backfeeding power into circuits it was never meant to control.
Rodrigues himself soon confirmed the diagnosis in the comments, explaining that a malfunctioning aftermarket remote-start module was the root cause. Once it was removed, the bizarre behavior stopped, and the car could be properly reprogrammed with a factory Cadillac key fob.
To the average driver, the idea that a car could start without a key, let alone from a headlight switch, feels like a violation of modern automotive logic. Today’s vehicles are built around multiple layers of electronic authorization, including immobilizers, ignition relays, and body control modules designed to prevent exactly this kind of thing.
Modern GM vehicles, including Cadillacs from the mid-2000s onward, rely heavily on a Body Control Module, or BCM, to manage everything from lighting and wipers to door locks and ignition logic. The BCM communicates with other systems over the vehicle’s CAN bus network, a digital communication system used across the auto industry. SAE International has published extensive documentation on how CAN bus architecture works and why unintended voltage signals can cause cascading system behavior.
When everything is working correctly, those systems are tightly controlled. When an aftermarket module fails, however, the results can look downright supernatural.
Aftermarket remote start and alarm systems don’t operate independently. To function, they tap into factory wiring for ignition power, accessory circuits, starter signals, and sometimes lighting circuits. Consumer-grade remote start systems are especially known for splicing into headlight or parking light wiring so the lights flash during lock, unlock, or remote start events.
If a module fails internally, often due to heat, age, corrosion, or poor-quality relays, it can unintentionally send voltage where it doesn’t belong. In this case, turning on the headlights appears to have sent a false ignition or starter signal through the failed module, triggering the engine to crank and start.
Automotive electrical experts have long warned consumers about improper installation of non-factory electronics and the long-term risks they pose.
While GM vehicles are often the punchline in comments sections, this kind of failure is not unique to Cadillac or even to American automakers. Nissan, Toyota, and Ford owners have reported similar issues over the years, particularly in vehicles equipped with aftermarket alarms or remote start systems installed long after the vehicle left the factory.
The common thread is the quality of the aftermarket components and the way they were installed. Factory systems are designed, tested, and validated as a complete electrical ecosystem. Aftermarket systems, by necessity, must integrate themselves into that ecosystem, sometimes imperfectly.
Technicians know the kind of electrical behavior shown in the clip can be dangerous. A vehicle that can crank unexpectedly poses risks in a shop environment, especially if someone is working under the hood or beneath the car. It can also lead to battery drain, damaged modules, or starter failure if the system repeatedly energizes components without proper shutdown sequences.
That’s why experienced mechanics in the comments section quickly moved past the jokes and into diagnostic mode, asking which circuits were involved and what triggered the starter. Their instincts were right: Isolate the aftermarket equipment first, then verify that factory systems still behave normally.
The Cadillac in Rodrigues’ video wasn’t haunted, and it wasn’t secretly designed to start from the headlight switch. It was doing exactly what a modern, interconnected electrical system does when it receives the wrong signals from a failed component.
The clip taps into a growing reality of modern car ownership: today’s vehicles are rolling networks of computers. When something goes wrong, the symptoms can look absurd, alarming, or even funny. But almost always, the explanation traces back to wiring, voltage, and logic, not magic.
Motor1 reached out to Rodrigues via direct message and commented on the clip. We’ll update this if they respond.
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