passenger seat occupancy sensor

[mwg51@cox.net]

I am getting a code for the airbag system that the passenger seat occupancy sensor has a problem. Can anyone tell me what I should be looking for under the seat. We recently bought the car and the fault light come on after we made a seat adjustment(electric /heated seats). I have reset the light but it still comes back on.

[DTU]

I have done some searching on this forum and it could eiher of the two problems.
It could be your sensor in the belt or the sensor mat in your seat. I am leaning to wards the mat. To replace this sensor would mean you have to take out the seat and remove the upholstry and then you can replace the mat. What the mat does is it checks to see if some one is sitting in the seat. It will disable the airbags if no one is detected.

I would start by checking the wires under the seat. If you don't want to replace the mat and want to get rid of the light, you can bypass it with this trick :w w w.apexcone.com/JimPowellHomepage/Recaros/Recaros.h t m l
( remove the spaces in the beginning and the end)

I will try to get this done as soon as possible, and I will let you know the result or vise versa.

DTU

[dano670]

Did you try the fix?

[Iron Chef]

How hard is it to remove the sensor without destroying the seats?

[tatawaki]

I think you have to remove metal pins to remove the leather to access the sensor.

If you find out that it is the mat, I'll give you 5 bucks for that connector that I need :P

[jsb008]

I took my 05 530i to a mechanic I know and had him read the fault code, passenger side seat sensor. I find that there is a recall and take to the dealer. They tell me it is battery linked in fuse and its over 600 dollars to fix. Does anyone know what you can do about the situation? thanks John

[aht bmp]

The fault code should be specific enough to troubleshoot what's wrong. Passenger seat occupancy sensor open circuit indicates internal failure within the sensor. The sensor is located between the large seat foam and the leather of the seat bottom. Here in the shop it means seat out, remove side plastic panel (where the switches are on power seats) cut the hog-rings carefully remove the leather off the seat, remove the old pad sensor, carefully ... oh so carefully reverse procedure then reset fault code.
A problem in the pre-tensioner of the belt or the buckle assembly has it's own fault code. A SRS fault for occupancy seat sensor is a problem in the seat sensor. If you're really careful and are comfortable with upholstery it's doable.

[aht bmp]

To answer jsb008's question, there is a recall (08V-384) dated 7/24/2009 to modify the mat to prevent future damage. It will not fix an already damaged mat. However, BMW NA has issued a service bulletin (SIB 65 75 06) dated 4/13/2009 for microcrack failures of the OC3 seat mat which extends 10 years or unlimited miles. Your vehicle doesn't exactly fit the E36 section you are in, but I hope that helps.

[flyfishvt]

That mat is not between the foam and leather. Its between the foam and the plastic basin the foam sits in. If it was between the foam and leather it would get torn to shreads. It is definately not held in by the hog rings. Ive had two sets of seats apart to take the heating elements out and install them in a different seat.

Its not a huge job to replace the sensor mat. You will however have to replace the four plastic pins that hold the foam to the bottom of the seat (plastic basin). It doesn't require removing the switches either but you will have to cut some zip ties to remove the wires. They simply fish up through the seat bottom. There's a bit more to it than that but that covers the big parts.

Please make sure you post accurate info.

[aht bmp]

Please make sure you post accurate info.

Thanks flyfishvt for your constructive criticism but accurate "reading" also applies. I didn't mention that the mat is held in by hog rings and if you do enough of these sensor mats you realize that they fail extremely often due to them not being well protected and developing micro-fractures...we perform this repair on multiple BMW generations in my shop frequently so I've seen this whole procedure done lots. Of course, we only do this for a living so maybe we don't know what we're talking about.

I wasn't responding to write a DIY, just a basic response to help mwg51@cox.net with a general sense of what would be at fault and a general sense of the scope of the repair. There's also more than one way to perform the job...like with any job.

We can all be helpful without making comments that reflect that we didn't read well.

[flyfishvt]

Sorry but you're wrong. The only thing between the leather and foam seat cushion is the heating elements. These are held in exactly as you described. Hog rings and all. The seat bottom sits on top of the occupancy sensor.

This applies to e36.

[aht bmp]

Flyfishvt is correct that the leather doesn't have to come off on the basic E36.

Here's a link for a decent writeup with pictures that shows the plastic tray under the cushion flyfishvt mentioned.

http://www.pelicanparts.com/bmw/tech...eat-Repair.htm

Hope that helps. Good call flyfishvt!

[Joylove]

Sorry but you're wrong. The only thing between the leather and foam seat cushion is the heating elements. These are held in exactly as you described. Hog rings and all. The seat bottom sits on top of the occupancy sensor.

This applies to e36.

+1.

[JDStrickland]

I have a question about this.

My car, '94 convertible, has had the SRS light on since I bought it 6 years ago. I have a diagnostic tool that can turn the light off, and the light will remain off unilt there is an occupant AND the occupant moves the seat in any of the adjustable directions. If the occupant sits wherever the seat is located when the light is off, the light remains off, usually. I've not paid any attention to the actual symptom set for several years, and I'm old enough that I've spent the vast majority of my life without airbags or ABS brakes, so I don't worry myself if they work or not.

I need to take my seats apart and replace the gear for the recliner motor, and I probably should look at the sensors while I'm there.

Do I understand correctly that if the occupant sensor is bypassed then the airbag will blow whether the seat is occupied or not? Right now, it seems to me that the airbag will not deploy even if the seat is occupied, and I'm not sure I grasp the significance of a deployed airbag in an empty seat.

If I wanted to turn the occupant sensor off by shorting it out, then the airbag will deploy in any crash, not just a crash where there is a passenger. What is the downside of that -- other than the cost of an airbag that didn't save anybody?

[tonysbone]

Sorry but you're wrong. The only thing between the leather and foam seat cushion is the heating elements. These are held in exactly as you described. Hog rings and all. The seat bottom sits on top of the occupancy sensor.

This applies to e36.

+1

You just need a new sensor and the 4 plastic "Christmas tree" pins to resecure the seat bottom to the frame.

Be careful drilling out the old plastic pins, I pushed a bit too hard, the drill slipped, and went through my left hand while doing this repair, so I guarantee the sensor is between the seat base and the foam!

[tonysbone]

This is a pic of my drivers seat when I was putting in new seat warmers and getting the leather redyed. There is no occupancy sensor on the drivers seat, but on a passenger seat, it would be a thin plastic mat lying on top of the plastic seat bottom(on the right hand side of the pic), but below the foam and leather bottom (seen upside down on the left of the pic)

Sorry for the poor image quality

[rustamabd]

There really is no need to mess with wires, black boxes, 200 Ohm resistors and any other such 'solutions'.

This issue is easily solved with software! Simply tell the MRS module to stop monitoring the seat occupancy sensor, done.

Using NCS expert, connect to the MRSZ module, and change the following two settings from aktiv to nicht_aktiv, like this:

ERKENNUNG_SITZBELEGUNG_1
    nicht_aktiv
ERKENNUNG_SITZBELEGUNG_2
    nicht_aktiv

The complete procedure is described in the attachment to this post (in German):
http://www.motor-talk.de/forum/e46-a...l#post32352082

[bluerooster]

There really is no need to mess with wires, black boxes, 200 Ohm resistors and any other such 'solutions'.

This issue is easily solved with software! Simply tell the MRS module to stop monitoring the seat occupancy sensor, done.

Using NCS expert, connect to the MRSZ module, and change the following two settings from aktiv to nicht_aktiv, like this:

ERKENNUNG_SITZBELEGUNG_1
    nicht_aktiv
ERKENNUNG_SITZBELEGUNG_2
    nicht_aktiv

The complete procedure is described in the attachment to this post (in German):
http://www.motor-talk.de/forum/e46-a...l#post32352082

Does that procedure not disable the passenger airbag? Or will the bag still deploy, even though the system has been de-activated?

[rustamabd]

Does that procedure not disable the passenger airbag?

It shouldn't*. Seat occupancy detection is an option separate to the passenger airbag:

From my ASW file :

. . .
PYRO
AIRBAG_F
AIRBAG_BF   <-- Airbag Beifahrer (passenger airbag)
SBE         <-- Sitzbelegungserkennung (seat occupancy detection)
SEITENAIRBAG
ZAE2_CI_05
. . .

* However, I have not tested it myself.

[flyfishvt]

Passenger seat occupancy sensor disables the passenger airbag if no one is sitting in the seat. That is exactly what it was designed for. If you disagree then tell us what that sensor is for.

[gramps33]

Flyfishvt is correct that the leather doesn't have to come off on the basic E36.

Here's a link for a decent writeup with pictures that shows the plastic tray under the cushion flyfishvt mentioned.

http://www.pelicanparts.com/bmw/tech...eat-Repair.htm

Hope that helps. Good call flyfishvt!

Hello, Reviving this old thread. I've got a 2008 Alpina B7. recently i got 9763 Open circuit, seat occupancy detector , driver's side. However, when i ohm out the seat mat, it's operating normally. I verified it's operating when you sit in it, the resistance drops from 325 kOhm to 31 kOhm. However, I don't know if this is the correct range. Does anyone know the correct range the vehicle airbag module is looking for?

Thanks!

[shogun]

you are in the wrong forum with your 2008 BMW Alpina B7, this is the E36 forum. But maybe someone can help you here too, otherwise post in the correct model subforum again your question

[gramps33]

Hi Shogun, yes I was aware it's not the right place for my vehicle but this post had the closest to good knowledge of the function of the seat occupancy system. These mats will all be in the same range of resistance readings so I was hoping some of the knowledgeable folks here could help!

Thanks!!