Siemens LMV 5 Series, Technical Instructions, Page: 212 / 374

Technical Instructions LMV Series
Document No. LV5 ‐ 1000
Section 7 Page 4 SCC Inc.
CANbus Faults Including “ AZL not on Bus ” and “ System Test ” (continued)
3. Check the LMV5 fault history. If the faults always occur in phase 38, the CANbus errors are
being caused by noise from the ignition transformer. Make sure the ignition transformer is
grounded properly and has a good neutral. Also, make sure any CANbus wires that run
close to the ignition transformer are in proper conduit. It may be necessary to either
relocate the ignition transformer or add a shield between the ignition transformer and any
nearby CANbus wires.
4. Unplug the 6 ‐ pin green connector plugged into terminal X51 on the top of the LMV5. This
leaves the AZL, the LMV5, and the cable between them as the only CANbus components still
plugged in. Reset the fault on the LMV5. At this point, two things can happen:

If the AZL faults with “Fault Feedback Air Actuator”, then the AZL, the LMV5, and the
cable between them are all working properly. This means that there is likely an issue
with the wiring of the actuators or O
2
module. Go to step 5.

If the same CANbus fault recurs, then there is a problem with the AZL, the LMV5, or
the cable between them. Check the wiring and terminations on the cable. Though
unlikely, the AZL or the LMV5 might be damaged and need to be replaced. If a spare
AZL is available, try it. If no spare AZL is present, check for any noticeable damage to
either the AZL or the LMV5 to determine which component to replace.
5. To find the wiring issue with the actuators or O
2
module, plug components back in one at a
time to terminal X51 on the LMV5 to determine which component is causing the CANbus
errors. First, plug in just the cable (unplugged from the actuator) that connects the first
actuator to terminal X51 on the LMV5. Reset the fault on the LMV5. If “Fault Feedback Air
Actuator” shows up again, the cable itself is okay. Next, plug in just the first actuator
(unplugged from the cable running to the second actuator). Reset the fault on the LMV5.
As long as actuator feedback faults continue to show up after each component is plugged in
and the LMV5 is reset, continue to plug in another component. At some point, plugging in a
component should cause the CANbus fault to recur.
6. Once the component causing the CANbus errors has been found, check the following to
correct the problem:

Make sure all terminations to the actuator are done properly and no wire strands
from adjacent pins are touching one another and causing a short.
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