w84me

Is the front passenger airbag supposed to be de-activated when there is not a front passenger present? In particular, should a yellow warning light be enabled in the overhead console when the front passenger is absent?

kscarrol

No passenger = no air bag activation = yellow light on
Passenger = air bag active = yellow light off

That's how it's supposed to work...

MiamiPhill

No this warning in the overhead console comes on when the sensors in the passenger seat detect weight that is less than is usual for the average adult.....i.e. a child, very small adult or some other heavy object.....mine was triggered by a carry-on bag once. In that situation the airbag is deactivated fo safety.

kscarrol

Right, or when the seat is empty. My light stays on when I have no passenger. Only when enough weight (50 lbs as I recall) is on the passenger seat, does the light go off, indicating the airbag is now active. But the sensor is not always very good and there have been recalls over this. Like MiamiPhill, a moderately heavy bag on the seat will activate the airbag, but I have had my wife sitting in the seat and the light NOT go off, indicating the airbag is not active. She weighs 115 lbs (don't tell her I told you that!) so the light should go out every time she sits in the seat. For bigger passengers like my dad, it goes off every time...

Rudy

Here's the way I understand things to work (but I could be wrong by a mile or so...):

First a little history:
I think the presence of the light has to do with the fact that children (especially rear-facing infants) can be severely injured by the deployment of an airbag. (I'm sure we've all seen the warnings, etc. about that.) Some time ago, in the US, the NHTSA (the governing body that mandates airbags on cars and light trucks) approved a switch for two-seater cars and pickup trucks so that the driver can disable the passenger airbag in case a child seat is installed. I think there ended up being many cases of people either forgetting to re-activate the airbag before an adult passenger used the seat or people forgetting to deactivate the airbags when a child seat was installed. This led to the development of different 'automatic' solutions like the M-B "babysmart" child seats which contained some sort of transponder in the seat that communicated with the car and deactivated the airbag automatically if the seat was present.

What I think ended up happening after some time is that the NHTSA mandated an automatic airbag disabling feature that was based on how much weight was on the passenger seat. Not only did this concept help reduce the amount of children injured by a deploying airbag but it also helped reduce repair costs after accidents since passenger airbags didn't deploy when no passenger was present. (Airbags are quite expensive to replace.)

Now to the part about the E60...

On my 2004 (pre-LCI) car, the light remained on any time that the seat was unoccupied and/or the seat contained an object that wasn't heavy enough to activate the airbag. The point was to allow a confirmation to the driver that the bag would not deploy in case a child was sitting there, etc. If a heavy enough object was detected in the seat, the light would go off indicating that the airbag was active (which would also trigger the "fasten seat belt" warning once you drove off.) The main problem with this setup was that the light stayed on all the time when no passenger was in the seat. Often times the light was a disturbance to the driver -- early on the light was very bright but it was fixed (or dimmed) in future builds and later software releases.

On my 2008 (LCI) car, they've made it a bit smarter. Now, the light stays off if no passenger is present (child or adult). It lights up if there's enough weight to detect a child but turns off if there's enough weight to detect an adult.

So to answer the OP's question, it depends on if your car is an LCI or not.

(Whew! Now ask me what time it is and I'll tell you how to build a clock... )

kscarrol

Well done Rudy! Did not realize how they had changed the system for the LCI cars, sorry about the misunderstanding MiamiPhill. Sounds like a good change as that light is quite bright in my 545...

Rudy

Before you know it, you won't be worrying about that bright light anymore...

w84me

Thanks for your replies guys. I am experiencing two issues on my 2004 545i Build Date of 2/2004

1) Sometimes it does not go out when my wife sits down - she is ~100 lbs. If she squirms around a bit, then it usually goes out. However, we have not completed our squirm tests to obtain conclusive evidence.
2) The other day when it was on because I had no passenger, I thought I would run a little test. I parked the car, and while it was running, went around to the passenger side and sat down. The light did not go out. I left the driver door open during this test in fear I would lock myself out with the car running.

Any thoughts or suggestions? Rudy, do you have the time?

Rudy

Well now that I can't duplicate your test since I no longer have a 2004 car, all I can suggest is that you fasten the seat belt while seated in the passenger seat.

Also, go ahead and take the plunge and close all doors. You're still able to turn the car off and take the keys before getting out of the passenger seat, right?

kscarrol

I'm curious to hear what's involved in the wife's squirm tests! Kidding, I'm kidding! We have had similar issues but it is so rare that my wife rides as a passenger that we've never dug deeper. Don't know if the open door is the issue but Rudy is right, go ahead and close the door. The car shouldn't lock until it moves. If the light does not go out, take it to the dealer. As I noted in my earlier post, the light sometimes went out for my wife but always does for bigger passengers like my dad or brother. As I recall there was a recall for faulty sensors way back when...