NIStune Type 1 Diagnostics - Manual (Page 9)

It might be necessary to clean up or push the probes through conformal coating which is a lacquer which
protects the circuit boards from corrosion.
(b) Next check the jumper settings are correct for the chip you are using
- Rev 3B-4 boards only have the PGM jumper which must be open during use in the ECU
-
- Rev C boards must have X1 (1-2) and X2 (1-2) for EPROM/Romulator mode or X2 (2-3) and X2
(2-3) for NVRAM mode. Also the J3 must be left unjumpered and J4 left unjumpered
- RevA/B boards must jumper X2 (1-2) and X4 (1-2) for EPROM/Romulator mode or X2 (2-3) and
X4 (2-3) for NVRAM mode. The wrong mode make still run the ECU but Nistune wont work