How do i know if this speedometer works???

[esotoracing]

HELP!! I have a porsche 911 electronic speedometer from i believe 1980's 911. It has 350 miles on the odo. Is there a way i can perform a test to know if it works or not ???
Can anyone help me with the part# and the code?
on the dialface 911 641 533 01 and 0023
stamped on the side body 437 201/1/12 T

THANKS in advanced!!

[3.2 CAB]

Plug it in and see if it works?? That part number, 911 641 533 01 crosses over to a superseded part number, that cost $472.00
It looks kinda odd, the speeds on the face

[Jim Williams]

Using a 12v battery and some test leads, put +12 on the + terminal, -12 on the - terminal and then alternate shorting and opening the 31b terminal to the - terminal using a third test lead or short length of wire. You'll have to do this rapidly to simulate the opening and closing of the reed switch at the 915 transmission sender. If you get some response from the Speedo needle, most likely the speedo works, but this isn't going to allow you to test how accurately it works.

Note that I'm posting this from memory of the terminal numbers, so I could be wrong.

[esotoracing]

Thank you very much

manufacturing date was 3\78