I am now on my third bad airbag seat occupancy switch for my 06 MCS. I'm guessing that a lot of you must be experiencing the same problem. The Z3 and Z4 boys have apparently been having the same problem and one of them has built a little plug and play resistor pack that you plug into the harness under the seat and the AB system thinks the seat switch is fine and well. Unfortunately, their system is apparently different from the MINI (thank you BMW).

Has anyone attempted to reverse engineer the signal that the AB system is looking for from the seat switch? All I want is the system to activate in full fashion in case I need it and the damn red light to go away. Can anyone offer any info?

YD

 

My daughter's '05 MCS with only 20,000 miles was diagnosed today with a bad occupancy sensor mat - dealer cost to fix about $800!!! The BMW fix is for a connector with two wires, the Mini has three. Anyone out there with a simple design for a bypass? How easy is it to replace the occupancy sensor mat?

 

The switch is actually a large mat sensor that is embedded into the upholstery of the seat.. every time I have had this done, I get a new bottom seatcover.

I don't know what happens when the switch goes bad, whether the airbag is removed from functioning or it just doesn't have the weight of the passenger info anymore and goes off at full force... I'd would think it would fail in a safe mode and go off with full force. I just want the red light to go out without me having to defeat the bulb. I want to know if some other part of the AB system goes bad someday. I have an AB rest tool which turns the light off for a few days, but it comes back on. I want a work around to plug in that tells the system to just fire away if I'm in a wreck.

I don't know if the system is looking for a specific resistance range or if it is sending a voltage to the mat and looking for a dif return voltage, or something else?

YD

 

On this car the red airbag light and the yellow "passenger airbag off" light comes on for a few days and then goes off again for a few days. It therefore seems as if the lights should extinguish by itself once the problem is repaired. This makes sense since the computer checks the status of the seat occupancy every time the engine is started. The dealer quote includes the whole seat cushion as you say. I plan to take it apart and see whether I can locate the fault, and secondly whether it can be fixed without replacing the entire cushion.

The dealer advised that even with the passenger airbag fault, the airbag will deploy in an accident, but it defaults back to the lowest force setting i.e. as if the seat would have been occupied by an infant. Regardless, it doesn't seem safe to rely on the passenger airbag deploying when the yellow light is on stating it is "off"!

 

Several people installed aftermarket seats and were unsuccessful at fooling the computer by using resistors. They resorted to removing the mat from the OEM seat and plugging it in (either just leaving the mat underneath the seat or installing it into their aftermarket seat cushion). Someone needs to measure what signals actually go through the connector for the mat.

 

Update, new trials from anyone?

I have a 2006 R50.

I am preparing to buy a 2.2 ohm resistor and place in series to give a general feedback resistance emulation of seat weight sensor as my car is out of warranty and price was $1000 to replace.

I may have read on one of these topics that the resistor is only good for the airbag sensor and NOT the weight pad?

thanks for any updates or if i have missed a forum (have found ~10 here and others).

 

Sorry I can't be of assistance. I gave up and traded the vehicle in on a Honda Civic. Hopefully no more electrical gremlins.

 

Please keep me posted. My passenger airbag light just came on a few days ago. As a matter of fact, it is only on when the passenger side seat belt is plugged in, and when the belt is not plugged in the light is not illuminated. I don't want to pay $800-$1000 to fix this and if I can do it with a simple resistor I most certainly will.

 

Put that 2.2ohm resistor in and watch your car do some crazy stuff.

2005+ seat occupancy sensor CANNOT be tricked with a resistor in the plug.

Try it and see.