NIStune Type 1 Diagnostics - Manual (Page 8)

3. Checking CPU connector header
(a) First check your cable connections are working. You need a multi meter and put it in to ‘continuity mode’
which makes a buzzing sound then the probes connect together.
Press the probes of the multi meter from the ECU connector side of the connection (either from the CPU
leg or jumper cable connector) to the board connector where it enters the Nistune board. See pictures
below
Later model NIStune Rev 3-4 boards checking from the header pin (D) to pin 1 on the Nistune board.
Earlier model Nistune Rev B board. Measuring CPU is connecting to the socket on the Nistune board