CAN Bus Electrical Test by sent by Email
to both Question 1 and Question 2 is 240 ohms.
If either wire, the CAN+ or CAN- wire is broken. the ohmmeter
will sense both termination resistors through the remaining good
wire which forms a series circuit of the two termination resistors
placed between the test lead probe tips.
120 ohms + 120
ohms = 240 ohms (The Law of resistance in series)
Hint: If you
don't see this concept consider this. An ohmmeter sends out an
ohmmeter test electron current through any circuit existing
between the ohmmeter probe tips. Start at the COM jack of the
ohmmeter and trace through the termination resistor on the right,
trace through the good CAN wire, then through the termination
resistor on the left and back to the Volt/Ohm jack on the ohmmeter.
You will see the test current flowing through the two termination
resistors in series for a total of 240 ohms.
across the CAN+ wire and it is good you will read 0 ohms or just
a few tenths of an ohm. If the CAN+ wire is broken you will read
across the CAN- wire and it is good you will read 0 ohms or just
a few tenths of an ohm. If the CAN- wire is broken you will read
Check out the
links on this web page if you are interested in more auto or
truck electrical electronics troubleshooting training. A good
place to begin auto or truck electrical training is with our
book "Electrical SHORTCUTS."