Red Alarm Light on Dash Board

[Frank.Hatfull]

Hi All
I am gradually finding my way round our Mercedes Devon.
The forum has been invaluable.
Just below the radio is a small red led and button.
It does not appear in the Sprinter manual so I think it is an AR addition.
The red LED illuminates when the central locking is on.
The button momentarily switches the LED off.
But I can't figure out what it's for.
Any information would be very welcome.
Kind regards
Frank and Mandy

[PLOUGHLIN]

Probably an alarm indicator. Standard Sprinter only has immobiliser. Most owners have an aftermarket alarm fitted, most can be integrated into the MB central locking control, so locking the vehicle arms the alarm, after 30-40 secs. Usually pressing the lock button during this time will switch off the internal sensors so, say a dog can be left in the vehicle or for use at night. Any alarm data paperwork in your papers?

[Frank.Hatfull]

Thanks for that.
It sent me off in the right direction.
I found a video on YouTube
It is the alarm override. You have to morse code the PIN number in using the button.
Thanks again
Frank