Infamous Problem

[Matched88]

so about a week ago i drove to college and everything was fine, get out of class me and friend get in car to go home and the airbag light is on...yay. the only thing that happened to my car while in class was get very very very lightly rained on, and my friend does not sit into the seat very hard or anything like that. so after further research i came across recalls, and other problems having to do with codes not showing up sometimes and seatbelts, P.O.S., and airbag control modules. so i get it to get scanned and all of the systems were scanned and the only codes that popped up were for the ABS, AC, and a code saying the power source or battery might be low or getting low, he resets the codes upon my request and i turn car off then back on and airbag light is still on along with the passenger airbag light near the shift knob is not lighting up at all no matter what.

Not sure where to go from here. possibly the occupancy mat/sensor? or would the codes i did have possibly make the airbag light come on or freak out?

 

[Matched88]

forgot to mention my vehicle is 03 2.5i

 

[Ricey01]

Did he/she move the seat?

I've has this on 2 different cars and it was just the connector under the seat getting pissed off at being moved or twatted by a rogue water bottle.

 

[Matched88]

The seat was not moved but i did have him slide it forward and back and lift it up to see if that would do anything, but i did find a bottle under that seat a day later when i looked under there. Is there a way to unconnect and reconnect that wire harness/plug under the passenger seat if thats it being loose?

 

[Ricey01]

I've never done it on the z4 but done it on the 350z. It'll prob be a block connector about an inch big. Unplug give it a bit of a blow and if your feeling really ambitious spray some switch cleaner in it. Reconnect and then I assume there is either an airbag reset procedure or you need some obdII reader to clear it.

With the 350 it's a load of key turning to specific timing but don't know about the z4

Would you look at that .......I actually helped someone

 

[Adamski]

Well done Ricey, its infectious

Does the warning sound come on too? Does the light come on when a passenger is sat in the seat?

 

[mac27040]

Get one of these if the passenger mat has failed, cheap option or get the mat replaced

http://www.ebay.co.uk/itm/BMW-PASSENGER-SEAT-OCCUPANCY-BYPASS-MAT-SENSOR-AIRBAG-E46E36E38E39E60E65M3M5Z3X5-/330695789403?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4cff014b5b&clk_rvr_id=368825264526


Sent from my iPad using Tapatalk HD

 

[Matched88]

ill have to give the connector a try and reallly hope that was the problem.

and no no sound comes on. the passenger on/off light near the shifter blips when car turns on but it does not turn on or off now when someone is in the seat, and the dash light just stays on even after a code clear.

 

[bcworkz]

:!: Disconnect the battery for a good while before playing with yellow connectors or you could trigger an explosion. :!:

You can't clear airbag errors with a typical OBDII tool. You need BMW DIS/INPA software or a dedicated reset tool.

A low battery can cause all manner of bizarre behaviour that will be resolved with a proper power supply. Don't attempt any repairs until you've ensured you have a good battery. There may not be anything else wrong.

 

[Ricey01]

:!: Disconnect the battery for a good while before playing with yellow connectors or you could trigger an explosion. :!: .

I'm intreagued......what exactly us going to explode?

 

[dmo]

Did you get this sorted? This happened on our SL. Had to get the airbag replaced as it was faulty. Hope this isn't going to be an issue on the z4 for me. I'd say move the seat around and check the connection. It could have moved out of place slightly causing the light to come on. Try turning it off and on too (key on/off switch for airbag is between passenger door and dashboard.

 

[bcworkz]

I'm intreagued......what exactly us going to explode?

Yellow connector under the seat, the seat belt pre-tensioner, which is an explosive charge. Takes up belt slack in an accident to limit excess movement and hence limit potential injury. The trigger mechanism uses energy from a capacitor which takes a while to dissipate, so a spurious change in state in the trigger wire could trigger the explosion, even if the battery is freshly disconnected. Other yellow connectors else where could trigger airbags. The tensioner would not likely hurt you, but the airbags certainly could. All of them will cause you to soil yourself and be expensive to replace.

Probably all very unlikely, but not something to chance no matter how unlikely.

 

[Ricey01]

I'm intreagued......what exactly us going to explode?

Yellow connector under the seat, the seat belt pre-tensioner, which is an explosive charge. Takes up belt slack in an accident to limit excess movement and hence limit potential injury. The trigger mechanism uses energy from a capacitor which takes a while to dissipate, so a spurious change in state in the trigger wire could trigger the explosion, even if the battery is freshly disconnected. Other yellow connectors else where could trigger airbags. The tensioner would not likely hurt you, but the airbags certainly could. All of them will cause you to soil yourself and be expensive to replace.

Probably all very unlikely, but not something to chance no matter how unlikely.

Bugger me!

Make sure I get the battery off then next time

 

[andysat]

Sounds a good point to remember

 

[Matched88]

yeah i dont mess with anything unless battery is disco. but nothing was wrong with connectors. yeah i doubt the scanner the place i had was a good one. it did check all the systems but none in airbag so i was like ehhhh. so im gonna buy a srs scanner so i dont have to pay multiple times at dealer trying to figure it out. ill have to get to my dads garage and check the battery to see how good it it still.

once the scanner is in ill keep posting until this s**t is fixed because i know this srs junk is annoying for a bunch of people.

 

[Matched88]

So my peake scanner came in today, was excited. turn key on plugged in followed instructions to scan and no codes read "ok cool guess i just need to reset." so i switched to the reset, ran it and the light didnt go off "guess i need to turn car off then back on afterwards." did that and light is still on....wtf....no codes and reset wont work.

 

[bcworkz]

I recall someone else had this problem, apparently the reset will not work unless there is a fault code stored. :headbang: Don't recall an outcome, but the plan was to invoke a fault by disconnecting a yellow connector and then starting the car. (after a proper series of disconnecting and reconnecting battery of course)

 

[Matched88]

the only thing that still bothers me is that the passenger airbag light still isn't working properly by always being on or the light being off aka its reading someones in the seat even if I'm alone. so I don't kbif that will fix with me causing a fault to reset the light or if that's is what is causing the light, just don't know why it wouldn't read a passenger sensor fault. I should prolly just take the seat out and reconnect everything again to be sure and put seat back in which from what I read that taking seat out and putting back in even causes a fault then I can reset to see if it will come back on and truely be the passenger mat/sensory

 

[bcworkz]

It's conceivable to me that the occupancy mat could appear to be functioning to the control module, and yet not be correctly sensing occupancy. But I have no idea how it detects a fault in the first place, so it's all speculation. What's inconceivable to me is how can the dash light be on and no faults stored? And yet it happens.

I think the occupancy mat is in fact faulty. Once it is replaced, or you fit a bypass, you should be able to reset the light. Note that if you fit a bypass, you may need to leave the seatbelt connected to avoid the seatbelt warnings. While you have things disconnected, regardless of which path you decide to follow, it's worth triggering an intentional fault so you will be able to reset the light once reassembled.