Looks like JetCat have a bit of work to do concerning screening of leads etc. from/to the ECU.
Using any old phone cable is not the best way to go I feel.
I once had a problem when my trasnmitter was about 6 inches from the phone cable from ECU to Turbine. Very strange things were being shown on the Graphic display. Took me about 1/2 hour to suss it out.