The go-to tool when there is no communication with the scan tool. Modern vehicles have roughly 15 to 25 computers all talking to one another on shared circuits. When those circuits fail, the vehicle may exhibit any number of problems.
The EEFF500 is a specialty tool that isolates the problem portion of the affected circuit quickly and easily. It features 12 switchable circuits and LED self-testing. Open circuits show up amber and short circuits show up red for easy detection.