V70: Electrical Air bag/seat belt warning lights

[bryanh]

My airbag malfunction warning and seat belt reminder light and 'bell' came on suddenly and simultaneously last evening. Do they have a common weight sensor under the driver's seat perhaps?
Is there a fuse I can remove to stop the bell while I'm waiting to get it fixed, as it is very irritating and distracting. And is it safe to drive, there's no risk of the air bag setting off whilst I'm going along?
Any ideas, suggestions welcome.

[Tatsfield]

These sort of errors are often caused by reduced conductivity in connectors in the firing/test circuits and a prime candidate is often the front seat belt pretensions which are pyrotechnic devices and monitored through the same system as the air bags. Because of their siting low down on the seats, the wiring passes under the seat and is vulnerable to damp which can cause corrosion in the connectors. This alters the value of the current passed when the test is carried out when the ignition is switched on. The current used to test the circuit is very much lower than that used to fire the device and so it is possible that the device is still serviceable and would protect you in the event of an accident but the test circuit is returning a reduced value and the ECU is registering a fault. The cure is usually to disconnect the connectors under the seat and clean them of corrosion and reconnect them. Also worth looking to see if the carpets are wet as increased humidity under the seats can bring on this fault. Some makes of car are more vulnerable to this fault than others and the quality of the electrical fittings has a direct bearing on this problem. I don't think it's that common on Volvos, but I thought I would mention it any way.

[bryanh]

Originally Posted by Tatsfield

These sort of errors are often caused by reduced conductivity in connectors in the firing/test circuits and a prime candidate is often the front seat belt pretensions which are pyrotechnic devices and monitored through the same system as the air bags. Because of their siting low down on the seats, the wiring passes under the seat and is vulnerable to damp which can cause corrosion in the connectors. This alters the value of the current passed when the test is carried out when the ignition is switched on. The current used to test the circuit is very much lower than that used to fire the device and so it is possible that the device is still serviceable and would protect you in the event of an accident but the test circuit is returning a reduced value and the ECU is registering a fault. The cure is usually to disconnect the connectors under the seat and clean them of corrosion and reconnect them. Also worth looking to see if the carpets are wet as increased humidity under the seats can bring on this fault. Some makes of car are more vulnerable to this fault than others and the quality of the electrical fittings has a direct bearing on this problem. I don't think it's that common on Volvos, but I thought I would mention it any way.

Where do I find the pretensioner connex? And how would I recognise them?

[Tatsfield]

Sorry I cannot advise as I've never had to investigate this problem on my Volvo. My experience with other cars merely highlights that this can be a problem but it does not enable me to identify which is the possible culprit connector. Your first action should be to run a diagnostics check with VIDA/DiCE which would narrow down you area of diagnostic search. Volvo dealers all have this disgnostic software but you can buy a Chinese clone system online which does exactly the same job on a laptop and would set you back less than a dealer would charge for a diagnostic session.