Quote:
Originally Posted by pokeybritches
Very interested. How does the weight sensor generally work? Does the resistance change when weight is added in certain areas? I guess I'm just hesitant to say that it will work exactly the same way as the Z4-specific occupancy sensor.
Let's say, for example, the M3 seat was wired in reverse of the Z4. From what I understand the airbags determine if they should deploy depending on the occupant's weight, and how that weight is positioned (correct me if I'm wrong). If the M3 was wired the reverse of the Z4, the computer that determines if the airbags should deploy will think the occupant is on the wrong side of the seat. The car won't throw an airbag light, but the system still isn't working properly.
If the M3's sensor works, it will be excellent for the Z4 community. I just think that in an area as critical as airbag deployment, you need to make sure everything works as it should.
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/start disclaimer
I'm not an expert nor are my comments in this thread anything more than an amateur's attempt to offer observations and opinions. Sorry, I'm sure you know this, but being in the legal field and this also being a discussion about a very integral safety system, I had to say it.
/end disclaimer
Very valid points.
So if by "reverse" you are referring to polarity, I suspect all of BMW's plugs are "keyed". BMW probably doesn't make female and male connector pairs that connect up fully that reverse things. Notice how every electrical plug in our car only fits one way and often locks? If by "reversed" you mean the physical route the sensor mat takes, you're right, it is possible but we can probably look at pictures of both and assume that if the route the flat wiring takes across the thin mat is generally the same then we're OK.
I'll snap a picture of the mat from the Z4 and will look for a picture of the M3 part.
Now, I do not *think* that the airbag system determines which airbags fire based on your location in the seat. I think it fires airbags based on presence which is a function of determining if the approximate weight of the passenger exceeds a certain amount. Perhaps by a change in the current? If you're over the weight, the yellow Passenger Airbag Off light is off. Now, the rate at which the airbags deploy is adaptive which I assume is, at least partly, based on the weight of the passenger. Not location of said weight in the seat because, though I'm no electrical engineer by any measure, I can't think of a way that you could gain that data from this mat.
I think we can also be comforted a bit by the fact that many occupancy sensor mats are used across multiple model lines. This tells me that the range of function is wide enough to work with different seat/cushion configurations which may impact the detection of weight detection and distribution.