Hi guys,

My S90 normally makes a springy noise from under the passenger seat (on my Right Hand Drive car, driver's side in USA/Canada) as I turn the ignition off, sounds like someone flicking the spring inside the battery compartment of a small electrical appliance, eg. flash light or TV remote.

Anyway since I got my S90 back from service a week ago, it stopped making that springy noise as I turn the ignition off, instead it would do it randomly when I'm driving the car. It did it very often the day I picked up the car from the mechanic, perhaps every 2-3 mins, then less frequent after that but still would do so every now & then. It seems more likely to do it if I've hit a bump on the road or turning the car on full lock. I suspect the noise is coming from the SRS crash sensor but can't be certain. Besides the SRS warning light on the dash extinguishes as normal after engine start suggesting no fault in the system.

Spoke to the mechanic who worked on my car, he said he didn't touch anything in that area, although when he disconnected the car's battery the siren with battery backup nearly blew out his ear drums (forgot to tell him I fitted one recently) and not knowing how to turn it off he hooked up a battery charger instead, which is the only thing that could've interfered with the car's electrical system.

Does anyone know what that springy noise is & how come it's doing it when I'm driving and not when I turn off the engine as it used to?