Matti,
Look at the connections on the back of the instrument first.
This instrument is has individual push in connections. If they are
poorly crimped or not clean, you will get nothing.
If that does not fix everything, look for splices in the 4-wire/shield
cable.
Sensor failures are relatively rare and seldom complete.
There is a good troubleshoot giude in the manual. If you do not have the
manual, it is available online at Raymarine.

Matt Colie
Yachtman's Technical Support
www.yachtek.com


Matti Raustia wrote:

Last summer it worked fine, now it shows only 0.00 kts. Other symptom is
that water temperature is -10 centigrades which is quite low... Any ideas
where to start looking for problem?

matti