Alarm Siren??

[SG]

I recently had to replace the siren unit in my 2002 C70 which had the same symptoms as yours.

The original siren was fitted with a NiCd battery pack which had leaked and corroded the PCB beyond repair. I was able to find a used replacement unit on eBay from a 2004 C70 convertible for around £35. The part number is 9466812. I don't think they are that hard to find and you might even still be able to buy them new (in the US anyway).

The replacement unit came with a NiMH battery pack, so they must have swapped from NiCd to NiMH sometime after 2002. NiMH batteries don't generally leak, so provided you can source a siren from 2004 onwards, the PCB should be good. I swapped the battery pack for a new one from here: https://www.ebay.co.uk/itm/Volvo-Car...53.m2749.l2649. If you want to save a few quid, you could make your own battery pack from four NiMH AA cells and just solder it to the board.

Swapping the siren is pretty easy. I didn't even have to remove the wheel arch liner as you can just fold it back at one side to gain access.

Once you've replaced the unit, you need to clear the fault codes to stop the LED light from flashing. You can do this using VIDA. There's a thread here that explains how to set it up: https://www.volvoforums.org.uk/showthread.php?t=310928. You can pick up a suitable OBDII adapter to use with VIDA for around £50-60.