Driver Seat Belt Light Flashing

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by sas0611, Sep 20, 2021.

  1. sas0611

    sas0611 Member

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    Today my wife started her 08' prius and the driver's seat belt light continued to flash even with her belt latched.

    Tonight I hooked up my laptop to the data port and looked for possible causes. There are no stored codes. The switch in the seat belt latch appears to be working correctly. The software reports when the buckle is engaged and when it comes out. The passenger seat weight sensors seem to be working fine - when I sit on the passenger seat i see values of upwards to 80 LBS is being reported.

    There is no weight being reported on the drivers side of the car. When I sit in that seat one of the sensors reports a negative value and the other stay constant at about 2 lbs. I would think that like the passenger side something would register when sitting in the driver seat since there is a set of sensors for drivers side of car. If there is no sensor in the drivers seat then this makes perfect sense that nothing is showing up.

    So my question is this - if the buckle is sensed when it is in the latch and if If there is a sensor and it is bad would this cause the car's electronics to disregard anything that is going on with the buckle/latch sensor since it thinks there is no driver sitting in the seat. Is there some connection between buckle/latch sensor and weight sensors on the drivers side.

    My wife will admit herself that she is a slob. There is a lot of things that find their way under the seat and behind it. It would not be far fetched to think that something dislodged a harness or broke a wire under her seat.

    Any thoughts would be greatly appreciated. Thanks in advance

    Steve
     
  2. ChapmanF

    ChapmanF Senior Member

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    I don't think the driver's seat has occupant classification sensors the way the passenger seat does. When the car is being driven it assumes it has a driver. So probably the buckle switch is where the action is going to be.
     
  3. mr_guy_mann

    mr_guy_mann Active Member

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    I looked at a wiring diagram and it shows dual-stage airbags for the driver and passenger. It also showed a driver's seat position sensor (as well as the driver's buckle switch) in addition to a "occupation classification sensor- front LH". The SRS system uses data from the Occupation Classification System ecu and the seat sensor/ buckle switch to decide whether to fire one or both stages of the airbag. If you have driver's seat weight in data then I would assume it does have OCS (like the wiring diagram indicates), and it should show something when someone is sitting there. If it doesn't show weight, then I might expect the system to set codes. What are you using to scan the car?
     
  4. sas0611

    sas0611 Member

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    Thank you for that information. I'm using the techstre
    Thank you for checking into this for me. I am using VCI with Techstream. There are no codes being set. The values are weird for driver side ( one is negative lbs). I will try and post a picture of the data list from the OCS ECU. There were 4 sensor (2 for right side of car and 2 for left). Each of the four had data for both Voltage and for Weight. Can you tell from your information where that sensor/wiring would be located and if there is any part numbers for it. I'm hoping it is just a connector/harness issue.
     
  5. ChapmanF

    ChapmanF Senior Member

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    I think the seat position sensor is the only thing there related to the driver's seat.

    The names of the four OCS sensors could trick you, because sure enough, they are called front LH, front RH, rear LH, and rear RH, but those all refer to the four corners of the front passenger seat cushion.
     
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  6. mr_guy_mann

    mr_guy_mann Active Member

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    Sneaky bastidges.
    So I was looking at the "right front" front LH OCS sensor.

    ocs data.jpg
    So here is a data list for the OCS with "normal" values. I'd imagine if something doesn't jive (such as registering weight - "not vacant" in the passenger seat- while the passenger buckle switch was "unset") then it would keep the dash light on.
    Posted via the PriusChat mobile app.
     
    #6 mr_guy_mann, Sep 21, 2021
    Last edited: Sep 21, 2021
  7. sas0611

    sas0611 Member

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    I would never have occurred to me that they were calling out the 4 corners of the passenger seat cushion....
    Thank you for enlightening me. Any suggestions regarding what's causing the buckle up light to keep flashing since it seems the that the Driver buckle switch is working perfectly - set condition reported when latched and unset condition when unlatched.
     
  8. ChapmanF

    ChapmanF Senior Member

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    Puzzling. Have you found anything useful in the related section of the repair manual?
     
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