Just months after the first official deliveries of the long-awaited Tesla Semi to PepsiCo and Frito-Lay in December, the truck has been hit with its first recall. When the truck is placed in park, the Electronic Parking Brake Valve Module (PVM) may not move into position, meaning an otherwise parked truck may roll.
According to NHTSA, only 35 trucks are affected by the recall. There aren’t too many concrete technical details about the Tesla Semi, so the recall is a rare look at the elusive truck’s subsystems. It uses air brakes like most conventional commercial trucks, of course, but it also mixes in regenerative braking from its Tri-Motor system which uses a twin-motor axle that prepares for acceleration and Another single-motor axle gets ready for highway cruising.
Tesla
The recall text calls the system an electronic parking brake, but commercial vehicles with airbrakes typically don’t use a traditional electronic parking brake like the ones you see on a car. With air brakes, the system fails on full application, meaning that if the system loses air pressure, the brakes will lock up due to the springs acting on the brake friction surfaces.
There are several air circuits on the semi-truck braking system, and a dedicated parking brake air circuit that holds the physical spring brakes back. It is unclear if the Tesla Semi uses this exact system, but the Department of Transportation (DOT) mandates a yellow parking brake valve that functions in the manner described above, and is pictured in the driver’s right hand side in the Tesla Semi. At the base there is an inner part. Whether or not there is a supplemental electronic brake is also unclear, although the fact that it is a parking brake valve rather than an actuator or motor is a strong clue to it being based around air brakes.
Tesla will replace the PVM in affected trucks free of charge and notify affected operators by May 23.
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