Quicker to search than find a picture to show, but @Alex 3 is right. Check the link below where someone else asked the same question:
Hi,When the alarm goes on all the indicator starts flashing but there is no sound.??
To replace the vacuum pump with the circuitboard it´s a $700 purchase in Sweden,
No,the interior lights doesn´t work when I opened the doors, but the work if I push the button.Hi,
That needs proper diagnosis ..............
I suspect it may well be the Siren, not the PSE assuming locking and Lights etc are working OK
The Sirens are about £80.00 new from MB
Hi,No,the interior lights doesn´t work when I opened the doors
Petri,Only within us