Seatbelt Warning Sensor is Too Sensitive

Discussion in 'Gen 2 Prius Main Forum' started by smarano, Jul 28, 2007.

  1. smarano

    smarano Junior Member

    Joined:
    Sep 14, 2006
    69
    1
    0
    Don't know if anyone else has experienced this but the seat occupancy sensor embedded in the front passenger seat of my 2006 Prius is WAY too sensitive. All it takes is a heavy package of groceries, or a tackle box, placed on the seat bench to set it off. I've resisted the temptation to deactivate the seatbelt warning beep because I like this safety feature, but I became really tempted this past weekend while lugging a bunch of groceries. Sure, I can always buckle the seatbelt to stop setting off the alarm, but I was wondering if it's possible to adjust the sensitivity of the sensor? If so, does it have to be done by a Toyota mechanic, or is it possible to do it oneself?
     
  2. hobbit

    hobbit Senior Member

    Joined:
    Mar 23, 2005
    4,089
    457
    0
    Location:
    Bahstahn
    Vehicle:
    2004 Prius
    Model:
    N/A
    I probed around with my finger and found the exact spot where the
    sensor switch is, near the middle of the seat. You can feel a
    slight bump there; it's the spot that takes the least pressure to
    turn on the light. I pulled out a Sharpie and *marked* it with a
    black dot. It's sometimes possible to move objects away from there
    to keep it off, but frankly even if it's blinking it doesn't bother
    me that much [the beep is long since turned off].
    .
    _H*
     
  3. dogfriend

    dogfriend Human - Animal Hybrid

    Joined:
    Feb 26, 2007
    7,512
    1,168
    0
    Location:
    Carmichael, CA
    Vehicle:
    2007 Prius
    I have a 14 lb dog and a 24 lb dog. The 14 lb dog can lay on the seat without setting off the alarm. The 24 lb dog always sets off the alarm. :p The threshold is between 14 and 24 lbs.
     
  4. Vebev

    Vebev Junior Member

    Joined:
    Jul 25, 2007
    28
    0
    0
    Location:
    Boise, Idaho
    Vehicle:
    2007 Prius
    I like to fasten the seatbelt around my groceries so I don't end up with them all over the car floor if I have to slam on the breaks.
     
  5. catgic

    catgic Mastr & Commandr Hybrid Guru

    Joined:
    Jul 7, 2007
    586
    139
    1
    Location:
    HTTP 404 Not Found
    Vehicle:
    2012 Prius v wagon
    Model:
    Five
    HTTP 404 Not Found
     
  6. lenjack

    lenjack Active Member

    Joined:
    Dec 1, 2006
    804
    112
    0
    Location:
    Pennsylvania USA
    Vehicle:
    2010 Prius
    Model:
    III
    My 2 dogs, 40 pounds will set it off. Any input on how to adjust the sensitivity would be appreciated.
     
  7. catgic

    catgic Mastr & Commandr Hybrid Guru

    Joined:
    Jul 7, 2007
    586
    139
    1
    Location:
    HTTP 404 Not Found
    Vehicle:
    2012 Prius v wagon
    Model:
    Five
    HTTP 404 Not Found
     
  8. jimmyrose

    jimmyrose Member

    Joined:
    Jul 14, 2006
    646
    3
    0
    Location:
    Northern NJ
    Vehicle:
    2010 Prius
    Model:
    III
    My soft briefcase (loaded with laptop and full legal sized folders) sets off the alarm, so I usually leave it on the rear driver's side floor or just bucklet the seat. I never weighed the bag, but one of my arms IS grossly overdeveloped compared to the other... :D
     
  9. FL_Prius_Driver

    FL_Prius_Driver Senior Member

    Joined:
    Jun 17, 2007
    4,319
    1,526
    0
    Location:
    Tampa Bay
    Vehicle:
    2010 Prius
    Model:
    I
    Look under the front passenger seat. Yeow, thats a lot of wiring to detect my wazoo. There are two measurement functions, the first sets off the seat belt buzzer, and the second (de)activates the passenger airbag system. As you can see, adjusting this fiddles with the passenger airbag system so the dealer may not be allowed to do this. The Toyota programming tool can calibrate this, but I did not see where it can grossly change this.

    Front passenger classification/

    AF05: Adult (36 to 54 kg (79.37 to 119.05 lb)) is seated

    AM50: Adult (more than 54 kg (119.05 lb)) is seated

    CHILD: Child (less than 36 kg (79.37 lb)) is seated

    CRS: Child restraint system and front passenger side buckle switch ON, then 7 to 36 kg (15.43 to 79.37 lb) is set

    OFF: Vacant[attachmentid=10239]
     

    Attached Files:

  10. lenjack

    lenjack Active Member

    Joined:
    Dec 1, 2006
    804
    112
    0
    Location:
    Pennsylvania USA
    Vehicle:
    2010 Prius
    Model:
    III
    Since we unfailingly use our seatbelts, I'm going to disable the sensor.
     
  11. IsrAmeriPrius

    IsrAmeriPrius Progressive Member

    Joined:
    May 27, 2004
    4,333
    6
    0
    Location:
    Southern California
    Vehicle:
    2005 Prius
    <div class='quotetop'>QUOTE(lenjack @ Jul 29 2007, 02:50 PM) [snapback]487193[/snapback]</div>
    Doing so will deactivate all the airbags and air curtains.
     
  12. diamondlarry

    diamondlarry EPA MPG #'s killer

    Joined:
    May 20, 2007
    559
    11
    0
    Location:
    Elkhart, IN
    Vehicle:
    2007 Prius
    It may be safer to just disable the beep for the passenger seat. Turn the car on and make sure the odometer is showing the car's total mileage and you are not on the trip odometer. Once on the car's odometer, turn off the car. Get someone to sit in the passenger seat and turn on the car while holding the odometer button down. Have your pasenger buckle, then unbuckle the seatbelt while continuing to hold the odometer button down and you're done. It won't beep anymore when the dog or groceries are in the seat and the airbag will still work if there is a passenger there.
     
  13. David Beale

    David Beale Senior Member

    Joined:
    Jul 24, 2006
    5,963
    1,953
    0
    Location:
    Edmonton Alberta
    Vehicle:
    2012 Prius
    Be aware, however, once the car senses something in the seat, the passenger airbag is activated, warning beeps or not. So if you manage to trip the airbags, it will cost you a lot more than if you had just placed your cargo in the rear or in the hatch area.

    But I do agree, the beeping is a little annoying.
     
  14. Dr Ed

    Dr Ed New Member

    Joined:
    Jul 15, 2006
    188
    0
    0
    Location:
    Texas
    Vehicle:
    2006 Prius
    I believe there may also be a sensor in the backrest. My teenager was in the back seat and leaned forward to talk with me while resting his arms on the unoccupied front seat backrest. Within 5 seconds his weight on the backrest activated the front passenger belt alarm.
     
  15. smarano

    smarano Junior Member

    Joined:
    Sep 14, 2006
    69
    1
    0
    <div class='quotetop'>QUOTE(catgic @ Jul 29 2007, 05:12 AM) [snapback]487021[/snapback]</div>

    What a helpful answer! Just the kind of information that Vebev and I were looking for! And so witty!

    Tell me, how do you suggest that I deal with the fact that my 12 year old daughter can also set
    off the alarm simply by resting her arms on the top of the front passenger seat back? Should I
    transport her in the rear cargo area also?

    Fortunately, for every would-be comedian who provides a witless answer that offers zero help,
    there are many more who are genuinely interested in being helpful.

    <div class='quotetop'>QUOTE(diamondlarry @ Jul 29 2007, 05:32 PM) [snapback]487202[/snapback]</div>

    Thanks, Diamond. Exactly the kind of help I was looking for.
    I just went out to the Prius parked in my driveway to attempt this and discovered
    that there's one step to add to your instructions. And with that, the front passenger seatbelt
    warning beep is gone. Good news is that - just like you indicated - the beep is the ONLY thing
    that's gone: the airbag sensor still works, the driver's seatbelt warning beep still works, and the
    front passenger seat warning LIGHT still works. Just the annoying beep is disabled. Perfect.

    Anyway, to add slightly to Diamond's instructions:

    1) Turn car on and make sure the odometer is showing the car's total mileage (not trip odometer).
    2) Once this is done, turn off car
    3) Get someone to sit in front passenger seat and then turn car back on (a full ON so that dashboard lights show) while holding in the ODOMETER button.
    4) Keep holding it and after at least 10 seconds, have the passenger buckle and unbuckle his/her seatbelt.
    5) You should now see a new message appear on the dashboard under the odometer reading: "B-on."
    Momentarily release the odometer button and press it again. The message should now read "B-off"
    That's it!
     
  16. FL_Prius_Driver

    FL_Prius_Driver Senior Member

    Joined:
    Jun 17, 2007
    4,319
    1,526
    0
    Location:
    Tampa Bay
    Vehicle:
    2010 Prius
    Model:
    I
    <div class='quotetop'>QUOTE(Dr Ed @ Jul 29 2007, 07:42 PM) [snapback]487215[/snapback]</div>
    Actually, there are only the four sensors at each corner of the seat. Each one is a weight sensor that adds up the total weight. It looks pretty involved and measures the weight of everything, including the weight of the seat itself and any rear passenger putting their feet on the seat, then removes the seat weight for sounding the buzzer and the light.

    Sooner or later someone will figure out a hack to display the passengers weight on the MFD. Everything is there.
     
  17. catgic

    catgic Mastr & Commandr Hybrid Guru

    Joined:
    Jul 7, 2007
    586
    139
    1
    Location:
    HTTP 404 Not Found
    Vehicle:
    2012 Prius v wagon
    Model:
    Five
    HTTP 404 Not Found
     
  18. smarano

    smarano Junior Member

    Joined:
    Sep 14, 2006
    69
    1
    0
    <div class='quotetop'>QUOTE(catgic @ Jul 29 2007, 07:31 PM) [snapback]487225[/snapback]</div>
    Noted. If I got a little heated, it's because I've read too many flippant answers that preach to forum members seeking help with legitimate problems and which don't offer useful help in return.
    For the record, I plan to have this oversensitive sensor looked at by my Toyota dealer when I next bring it in for service. I'll post my experiences. And, for the record, I don't plan on discussing the disabling or overriding of passenger safety systems during family conversations, as you presumed.
     
  19. skandale

    skandale Member

    Joined:
    Jun 11, 2007
    101
    0
    0
    I'm having problems understanding how a 12 year old girl sitting in the back seat can rest her arms in the front seat backrest. I would assume that any person travelling in the back of the car would use seatbelts just as you do in the front. Basically all the car's safety features assumes that all passengers are fastened at all times. All airbag systems rely on that to function correctly.

    As for Norway, using seatbelts has been mandatory (where-ever you sit in the car) for several decades.

    Just my thoughts....

    Stein
     
  20. catgic

    catgic Mastr & Commandr Hybrid Guru

    Joined:
    Jul 7, 2007
    586
    139
    1
    Location:
    HTTP 404 Not Found
    Vehicle:
    2012 Prius v wagon
    Model:
    Five
    HTTP 404 Not Found
     
Loading...