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

Edmunds.comEdmunds.com Member, Administrator, Moderator Posts: 10,316
edited March 2016 in Jeep
imageBelieves 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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Comments

  • iamthestigiamthestig Member Posts: 85
    My Passat dings at me when I have a couple of bottles of water and my phone on the front passenger's seat. It's so annoying!
  • saxdoggsaxdogg Member Posts: 38
    Nice references.
  • 5vzfe5vzfe Member Posts: 161
    My car only does this for heavier objects and even then there's only a flashing light on the passenger side of the center console. I put bags and stuff on the floor though since they will slid off anyway if you have to brake hard.
  • pinhead_907pinhead_907 Member Posts: 8
    Looks like that brief case is kind of attempting to compensate for something anyhow. Next time get a slimmer European carryall - you should be fine.
  • thecardoc3thecardoc3 Member Posts: 5,824
    edited March 2016
    Hi James. The question you should be asking yourself, is why are you putting your briefcase on the passengers seat in the first place? Do you have any idea what an unrestrained object like that is capable of doing in the event of an accident? Think of it this way. Would you be willing to stand there and let someone swing that as hard as they possibly can and hit you with it? Now imagine it being swung three or four times harder than that and you have a picture of what could happen in an accident.

    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.
  • desmoliciousdesmolicious Member Posts: 671

    Hi James. The question you should be asking yourself, is why are you putting your briefcase on the passengers seat in the first place? Do you have any idea what an unrestrained object like that is capable of doing in the event of an accident? Think of it this way. Would you be willing to stand there and let someone swing that as hard as they possibly can and hit you with it? Now imagine it being swung three or four times harder than that and you have a picture of what could happen in an accident.

    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.

    What he said.
  • darthbimmerdarthbimmer Member Posts: 606
    edited March 2016
    I believe the way cars weigh what's in the seat is fairly primitive. Like, a few pressure sensors and a potentiometer that can be adjusted. When as little as a 5 lb bag triggered the chime in one of my cars the dealer adjusted the pot to set a higher threshold.
  • thecardoc3thecardoc3 Member Posts: 5,824
    What car has an adjustable potentiometer for recalibrating the passenger presence system? There are none that I know of. It is possible to do a recalibration on a number of models, especially ones that use a zero point initial setting where the system could be lied to but that causes a potential problem. If what you wrote is accurate, the system might not function correctly when the seat is occupied by someone who weighs between seventy and ninety pounds. (Rem spec for suppression is 79.37lbs) If the system has been tricked to start out with a higher weight, then it will take a heavier person than it is supposed to for it to abort suppression.
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