[02420X3]

I've noticed an odd situation where the passenger seat safety belt indicator lamp and gong will sometimes activate when I have no passenger, but have two mobile phones on the passenger seat.

I have two mobile phones, a work Blackberry and a personal iPhone. When I drive, they're both usually plugged in for charging (lighter adapter for the Blackberry, USB port for the iPhone), and they're both usually laying on the vacant passenger seat.

Occasionally, not always, and anywhere from 5 to 15 minutes into a 30-minute drive, the passenger safety belt indicator lamp will light, the unfastened safety belt gong will sound, and both will continue until I move one of the phones to a cup holder.

Has anyone else seen this? Any thoughts on the cause? I'm guessing that it's some kind of RFI from the phones.

[kozzi]

It may have something to do with the weight of the phones on the seat. There are sensors in the seats. If a passenger is seated in the side seat, the front and side airbags are active (for that seat position). No passenger and they are disabled. Does the same thing for seatbelts and bongs until the passenger buckles in. Next time this happens, check to see if the airbags are active or not. There is an indicator light in the center of the headliner above your head (where the moonroof controls are if you have one installed).

The weight of 2 smartphones should not be enough weight to "trick" the vehicle into thinking there is a side passenger seated so I would have this checked out. Don't take chances on that sensor failing when you need it...like in an accident.

I have rested my ipads on the side passenger seat many times and never had any issues. I would get it checked out right away.

[02420X3]

Kozzi, you've asked a good question. I looked up at the overhead indicators, and the airbag sensors think that the seat is empty. The airbag is disabled for the passenger seat, yet the seatbelt lamp and gong have still activated.

When it first happened I had 2 lbs. of fruit (breakfast and lunch) and the two phones on the seat. I've taken the 2 lbs. of fruit out of the picture, and now it's just the phones, nothing else, and the weight is not an issue.

Still, with the two mobile phones, I get the occasional lamp/gong issue.

[Lotus7]

It’s a long shot explanation, but it is conceivable that the RF radiation from one or both of the phones is leaking into the seat weight sensing circuits and triggering the warning display/gong. Even if the phones are not actually transmitting or receiving they can send out short RF bursts when moving from one cell to another if on.

With the phone(s) inside of a car, sitting on a seat, they are probably running at the highest of the three possible transmitter levels (600 mW). That much RF a few inches away from the seat weight sensor wiring could possible be rectified and could generate an interfering signal. It's unlikely that the seat sensor wiring has much in the way of RF filtering.

You might try a drive with the phones in place on the seat, but with them completely shut off or in airline mode. If the light still triggers it’s not RFI.

Alternately, try a different object about the same size and weight as a phone, but with no electronics - maybe a small book or wallet. If the light still triggers, clearly it's a dynamic weight issue of the weight bouncing on the seat sensor, or possibly a loose connection in the seat. If that's the case, then clearly you're due for a trip to your dealer for repair.

[sfax]

Originally Posted by 02420X3

Kozzi, you've asked a good question. I looked up at the overhead indicators, and the airbag sensors think that the seat is empty. The airbag is disabled for the passenger seat, yet the seatbelt lamp and gong have still activated.

When it first happened I had 2 lbs. of fruit (breakfast and lunch) and the two phones on the seat. I've taken the 2 lbs. of fruit out of the picture, and now it's just the phones, nothing else, and the weight is not an issue.

Still, with the two mobile phones, I get the occasional lamp/gong issue.

I think you have a fault with the sensors and would take it back to the dealer. I often put quite a heavy bag on the passenger seat and it has never set off the gong

[02420X3]

Lotus7,

You and I are thinking alike on this issue. Thanks for the suggestions.

Sfax,

I think that I have eliminated weight as an issue. Were my laptop bag or my (heavy) lunch an issue then the problem would have disappeared when I relegated both to the back seat. If there is a fault then I think that it is an RFI issue. I will continue to monitor, and will bring it to the dealer when I am certain.

[sfax]

Originally Posted by 02420X3

Sfax,

I think that I have eliminated weight as an issue. Were my laptop bag or my (heavy) lunch an issue then the problem would have disappeared when I relegated both to the back seat. If there is a fault then I think that it is an RFI issue. I will continue to monitor, and will bring it to the dealer when I am certain.

Yeah, sorry, I meant it's unlikely to be weight as your phones weight 100x less than the bag in question. Could be RFI or just an intermittent fault that happens only to have been triggered when your phones were on the seat. Would be interested to hear if you think it's definitely the phones.

[kozzi]

Not a weight issues if the airbag indicator senses that the seat is empty. You mentioned that the phones were being charged at the time. Try placing the phones without them plugged into anything charging and see what happens. Seems like Lotus and Sfax are ont he right path to the cause of the problem. Either way, it's a trip to the dealer. Let us know what happens. Good luck.