We have a Lowrance LMS 332C dash mounted on our Stratos and its a great graph, but we're having issues with it. The graph works flawlessly, but whenever the outboard is started, the graph shuts off. It then needs to be manually turned on again. Its pretty frustrating to have to restart the unit every time the key is turned. I'm afraid the problem occurred after a road trip. I took the graph off the dash, but failed to secure the 3 cables attaching to the unit itself. I'm afraid they were flapping and waving in the wind on the way home and somehow became damaged. Right after that trip is the first time we noticed the problem. Does anyone have any suggestions what the issue is or a possible fix? Thanks

I had the same problem with my unit one time.  I cleaned all the connections, even checked the fuse holder connections , next I charged my cranking battery.  Next time I took boat out I had no problems.

As mentioned, dirty/corroded terminals will cause it.  A weak battery will also cause it in a heartbeat.  Place a voltmeter across the lead terminals on your battery, crank the motor and see how much the voltage drops.  It should still have more than 12VDC when cranking.  If it's dropping much more than that, I would get me a new and bigger cranking battery. 

If it checks good checking across the lead post, connect to the terminals on the battery cables and check it again.  If it drops more there than it did on the battery, you terminal connections are dirty.  Remove them and clean them good.   

Good advice above, and in addition, if your unit power cable is not directly wired to the starting battery, also check all wire splices, switches, fuse links, etc. in line from the unit power cable under the dash back to the battery.  Could be your battery, but most often a poor wire splice or a bad switch is the culprit.  As mentioned before, a voltmeter (not a test light) is a must when troubleshooting this.  If input voltage drops below 10.5V, the unit will shut off.  A faulty splice or switch may still have some voltage passing thru, but it may be less than what's required.

To test voltage thru the unit power cable, place voltmeter leads in the two largest pins of the cable.  Be careful only to touch those two pins or you will blow your inline fuse.  Also, you likely have the spring-loaded, inline glass fuse holder.  If so, replace this with the auto style blade fuse holder while you are troubleshooting.  If the glass fuse holder isn't at least some of your trouble source, it will be down the road.