This is most commonly caused by having the incorrect harness plugged in during part 1 of the Cummins Unlock.
Part 1 requires the "Stock" harness that is included with the GT to be used.
If you have the "Unlock Harness" plugged in during part 1, please unplug and restart the unlock using the "Stock" GT harness. (Pictured below)
Our Technical Support team is here for you.Contact Support