Whatever this thing is, it used to have a shallow, conical steel disc covering it. I managed to lose it and now I don't know what it is or how to buy a new one. It has a connection to the wiring harness--some sort of sensor? Outside temp maybe? Maybe emissions?

If it's hard to tell, it's located on the center of the firewall. You can see the windshield above it and the piping to the turbo to the right. This is the view from the front of the car.

 

It looks like a siren/horn bracket.

Wait for others to reply....

 

I always thought that was where the engine compartment temperature sensor was. On my car there is like a cap on that which looks like some kind of sensor.

 

Nope, thats the car alarm. Mine went out. replaced it with a Clifford and my car chirps now!

 

Yes that is the alarm siren but there is a big washer looking thing missing.(Very common)

 

The missing washer like looking thing is a viberting plate that makes the sound. It is very easy to loosen it or probably it loosens by itself over time and then drops. This is just another regular horn connected to alarm circuit. If someone wants to replace it, then you can just but a regular horn/siren and connect to same wires and you will have your alarm functional again.

 

LOL, that was funny. After getting my daughters' S70 we decided to test her alarm. It sounded like someone trying to clear their throat. I thought the thing was shot so I planned to pick anotherone up from the area Volvo salvage yard the next time i was there. Then about 3 days later I tested it again and seen it vibrating so I grabbed the end of it (the **** in the middle) and it was very loose. I tighened it and it sounds good now. Nevery seen anything like it before, it has an adjustment to change the way it sounds.

 

You know, I accidentally set the alarm off the other day (got out at a gas station, used the remote to lock it so my gun would be locked in the trunk, but then reached in through the open window and pulled the lock button to get in) and noticed that it set off the flashers and disabled the car but was silent. It never occurred to me that it ought to be making noise.

Thanks!