In the picture you see on the left side the progaming socket from the speedometer.
On the right side yoz see the main socket for main cable of the car.
When you are programing you let the powersupply for the car(12 Volts)connected to the speedometer.Or you make your own powersupply to the speedometer.
On the second picture you see a selfmade plug.The pins 1,2,3,4 are the same as in the wireing diagramm.
On the next picture you see the plug and the pins 1,2,4.Pin No. 1 is at the guiding from the socket
wlodek57