Figure 5-2 Correct Can Bus Terminator Example - Garmin G5 Maintenance Manual

3) With power removed, remove the CAN bus connector from one of the devices that is not located
at either of the extreme ends of the CAN bus.
a. Using an Ohm meter, verify the resistance between the CAN-H and CAN-L pins on the
connector is 60 Ω. This will verify the CAN backbone is properly terminated at each end
(two 120 Ω terminating resistors in parallel).
b. A resistance of 120 Ω indicates one of the two required CAN terminations is missing.
c. A resistance of 40 Ω or less indicates too many terminations are installed.
4) Verify the CAN-H and CAN-L signals are not swapped, shorted together, or open-circuited at any
LRU connector.
5) Verify the CAN-H and CAN-L signals are not shorted to ground.
6) Highlight each device on the configuration mode Device Information page on the #1 G5 unit and
verify the value displayed for Network Error Rate is a steady 0%.
7) Power up the #1 G5 unit and one other CAN device at a time and verify the connection quality
for each device. Sometimes a device will communicate only when it is the only powered device
on the CAN bus if one or more of the above issues is present. Evaluating each CAN device in
turn can help narrow down a problem.
NOTE
If a Lightning Protection Module is installed, check for continuity between backshell leads per
Garmin G5 Electronic Flight Instrument Part 23 AML STC Installation Manual, 190-01112-10
section 5.
Garmin G5 Electronic Flight Instrument Part 23 AML STC Maintenance Manual

Figure 5-2 Correct CAN Bus Terminator Example

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