When Lonsdor K518ise gives you error message “Cuommunication failure, code :3A1” and you have connected main cable well and selected correct system, you can check the device voltage to see if the battery power is low or not using a digital multimeter.
How to test the voltage of Lonsdor K518?
power off the k518 and plug in the original power cable
Turn the multimeter to 20v
use the red electroprobe to touch the metal part of the k518
If there is something wrong with your device voltage, please contact our customer service.