Believes My Briefcase is a Person - 2015 Jeep Renegade Trailhawk Long-Term Road Test


The 2015 Jeep Renegade Trailhawk's passenger seat seatbelt warning chime is a little hypersensitive, instructing one of our editors to belt a briefcase that normally goes unnoticed.
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Passenger presence systems are in place because the engineers don't want to have a full airbag deployment if there is a child in the front seat. Calibration levels are in the 60lb to 74lb range across almost all of the manufacturers. The specification for airbag deactivation is 79.37lbs OR LESS. To the car, your briefcase looks like a small child because all it does is weigh the front seat. Meanwhile the switches in the seat belt buckle inform the system that the seat belt isn't buckled and that has the potential to add up to a tragedy. So the car warns you about it, it's supposed to.
It works like this: If the system detects weight on the front seat, the fist concern for the engineers is that the occupant whatever it is has to be kept out of the danger zone should the airbag need to be deployed in the event of an accident. The danger zone, or "punch out zone" is the first two to three inches from the dash where the airbag has to break through the vinyl cover. If a child or small adult is in the punch out zone during a deployment it can cause serious injury, or even death. (Think about that for a few minutes while you rethink your need to write about your displeasure with the system). If the seat belt isn't buckled then inertia could allow the occupant to move into the punch out zone during braking prior to the accident and deployment. It might seem like a contradiction here, because if the system detected a "child" it shouldn't deploy, right? Well......
If the primary restraint system (the seat belt) isn't being used then the secondary system might be the only chance the system has to protect an occupant. That means in the event of a crash, in order to try and protect the occupant, the system may have to decide to do a full deployment of the airbag. This would be the worst thing to have happen if an unrestrained small child is in the front seat.
That's what it looks like to the car, and the engineers got it right when the car tells you to do something about the situation. There is a lot more to the system than this brief explanation but there is no sense writing an entire class on it.
So.
Put your @#$%^ briefcase behind the front seat on the floor where it belongs and thank the engineers for designing a system that's smarter than you gave it credit for.