CAN network explained. A CAN Bus can fail in different ways and can cause a no communication with the scanner, in some cases it can cause a vehicle not to start. Here are different test you can perform using only a multimeter. You can perform a voltage test to see if the Can bus is active or shorted. You can use a resistance test to check the terminating resistors and to check if the network is shorted. Check out the bect video to know how to test the CAN bus with an oscilloscope.