COMPONENT: Trailer parking brake and its release circuit, including a connector in the button box on the front of the trailer. The trailer is available for inspection on request. 11/22/25 I hitched the trailer to my tow vehicle (Tesla Cybertruck), raised the jack, and released the trailer parking brake from the tablet supplied with the trailer, as the manufacturer specifies. The brake released. This produces a distinct jolt felt in both vehicles and the tablet confirmed it. As soon as the vehicles began to move,...
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the parking brake re-applied itself with no command from me and no warning. The tow vehicle strained well beyond the load, and on stopping I found a drag mark about 7-8 feet long on the pavement where the trailer had been dragged with its brakes engaged. CAUSE: Water ingress into the button box corroded a connector, producing an intermittent electrical contact. The brake circuit treats loss of continuity as a command to apply the brakes, so the intermittent contact was read as a brake command. Salt residue was visible in the connector. I photographed it. CONFIRMED BY MANUFACTURER: Yes. Pebble Mobility opened case CASE1099 on 11/22/2025, sent a technician, inspected the trailer, replaced the affected component and improved the sealing of the enclosure. It has not recurred. The removed part should be in the manufacturer's possession. WARNING BEFORE FAILURE: None. No warning lamp, message or symptom preceded it. SAFETY RISK: I accept that trailer brakes must apply on a genuine breakaway. My concern is that this design appears to make no distinction between a real disconnection and a momentary loss of contact - no filtering or debounce that I can determine. Corrosion is only one cause. A wire cut by road debris, a chafed conductor, or a marginal connector jolted by a pothole would interrupt the circuit the same way and apply the trailer brakes at whatever speed the vehicle is traveling. Mine failed at walking pace. At 65 mph this would be far more serious.