Apparently not. Orangecrush just got JCW seats for his R56 and has an ongoing thread on NAM about installing them. The weight sensor has a microcontroller circuit that talks to the computer on the data bus. This can be seen in the wiring diagrams. To bypass it would require someone like Ian Cull (developer of windows up circuit) to analyze the messages and come up with a circuit to mimic it. Some people have even reported that if you change the sensor mat (new or from a different car), the dealer needs to program it into the computer. The sensors may have unique ID's and the computer has to be told to recognize it.
DAMMIT! I was going to buy another sensor, if I could find one. I have no desire to rip the one out of my english panther leather passenger seat. I wish there was an easier workaround. Wonder how hard it would be to remove the light itself.
If you measure the Ohm rating of the sensor you should be able to just get a resistor that would work for it. We've done this with the airbags... this isn't any different. It maybe even easier and just need a closed circuit.
I have found this to not be the case. If you look at the install guide that I wrote up, there is a picture of the seat mat in question. I have used resistors for both airbag seats as well as the two airbag circuits that are in the steering wheel.
I don't see how just a resistor could work. The connection to the mat assembly is a data bus. You need the microcontroller circuit to talk to the computer and it comes with the mat. Maybe a resistor could work if you want to ditch the mat itself, but you would be putting it on the circuit board and you still have to start with the full mat assembly.
Again, they wouldnt be the same as the air bags. But the point is it's a switch. When it is "on" (someone sitting on it) It either sends a signal or closes the circuit.... etc. A simple multimeter with ac/dc/ohm/continuity should be able to give you the information needed to figure this out.
But isn't it a "Smart Switch" that knows when the weight is less than X for off. Also can determine the force to deploy depending on weight when on.
Right, so my point is at some point its "ON" So make it so it's on. Are you people with JCW and other race seats really putting a baby seat in the front?
That's what I'd like--just leave it on all the time. There's no reason for it to be disabled in my car; there will never be anyone other than an adult in there anyway.
When I had the seat mat out of my car, I did put a meter on it and the data was not helpful. I can't remember now exactly what the reading was, I think it just showed zero resistance. Again, I have fooled the airbag system on both seats as well as the steering wheel (I have a sparco wheel), and the seat mat is different.
The mat is connected to the car through a DIGITAL data bus. You can't fool it with a resistor! This is different from the airbags. There are two components to the mat assembly: the actual sensor mat itself, and its electronics on a circuit board. The sensor mat portion is maybe replaceable with a resistor but the electronics portion is needed for communicating on the data bus. You can't get away without an OEM mat entirely -- you will need at least its digital controller. This is a pic by orangecrush from his seat swap with the circuit board visible.
Yikes! They do make it complicated, don't they? So that's why my car starts gonging at me when I have a 12lb Mini-pooper in the front seat.....
Well what exactly does the board do. It's going to change a signal right? Then the bag turns on or off based on what? The pressure on the seat being X weight makes it flip a switch? What's it doing BEFORE the bus? etc etc etc It's really not that complicated. Maybe it is, but it just takes time. I mean, you only have to be smarter than the mat! Frankly I'd do it my self if I had one. But I dont need to as I have an 04...a... and 2 it doesn't have an airbag there anymore due to harnesses. Maybe instead of saying how it can't be done. Someone could be helpful and figure it out? That seems like a neat idea.
I agree 1000% with this attitude! I think ironically the rate of change of our society has tended to cause people to know more & more about less & less...which has the side effect of making them hesitant to tackle things outside of their (very narrow) "comfort zone". There is nothing magical about this stuff. Here's how I would approach it: Looking at the diagrams from that site, it looks like the airbag signals back to the computer via the K-Bus (i.e. CAN bus). This is a simple serial bus protocol (i.e. the modern equivalent to RS232). Given that there are no other signals coming into the mat, it should be a fairly "dumb" interaction with the airbag controller...i.e. either a simple request/response pair, or even just a continuous output from the pad. A simple $10 stamp computer should be able to reproduce this behavior. And it should be possible to look up the necessary parameters (i.e. bus speed, error bits, request/response format, etc.) or figure them out via experimentation. One caveat on this: Unfortunately error codes in the airbag system are often permanently logged (i.e. there's no way to clear the error codes from the system). And it may not like it if too many error accumulate. So you might inadvertently disable the airbag system if you experiment too much. Probably not in the trivial category, but definitely in the doable one.... My 2c
Yes, "all it takes" is to sniff the bus and have a microcontroller mimic the behavior. However that's a big step from the resistor and beyond the capability of most DIY enthusiasts. There is a market opportunity if someone would actually do it and offer a solution.
Perhaps I'm misunderstanding your point, but my experience has been just the opposite. For example, most magic tricks seem trivial once you know the secret...