lowrance 3500 depth guages -- why 2 of them?

[wilsonalexander]

I have a new to me 99 response lx with two lowrance 3500 guages. The faces look identical but they have different functions. One is a depth guage and it allows me to set the shallow and deep water depths. When I leave it after setting the values, it reverts to flashing 0.5 ft. While operating the boat, sometimes it flashes 0.5 ft and sometimes a ridiculous value like 942 ft (my lake has a max depth of 30'). Is there something I am missing? Is the transducer faulty, is the wiring buggered up?

The second lowrance 3500 seems to give me time of day, engine hours, water temp (not sure what else it will do). I have no manual for either unit and don't know how to set the second one. Does anyone out there have similar guages in their boat? Can you give me some guidance of how to operate/troubleshoot these guages?

[edwin]

one the depth gauge, other is a water temp gauge (also shows volts, hrs, etc)...was part of a package back then. email Lowarance and they can get you operating info on those units

[jgouveia3]

the flashing .5 means it is not getting an accurate reading. Lowrance will tell you its either the gauge or transducer (very helpful). They will also say to send one or the other in, and for $49 they'll tell you whats wrong. you can find new units for $99. I just let mine blink, since i am always on the same lake.