How to fix Pcmtuner Unable to use selected interface J2534 Scanmatik SM2 USB?

Feedback: problem with Pcmtuner ecu programmer, it often disconnects, I changed my usb cable still the same, it says “Unable to use selected interface J2534 Scanmatik SM2 USB” shown as below.

Possible reason and solution:

It will do this if using some OBD modules if you are not using scanmatik interface, you need to cycle ignition between ID and Write routines.

This happens because huge voltage drops when trying to connect to ecu. If youre power supply cant handle the current and will drop the voltage under 11v , it usually disconnects… Tested myself… When used 12v, 7a, high quality power supply, it does not disconnect…on my pcmtuner with power brick from the box , i had 2.7v voltage drop on a edc17c50 with some random disconnection… With the 7a one i had like 0.6v drop and no disconnections…

Pcmtuner tech support: