I have a 1198 on my 2012 BassCat. When i bought the boat a year and a half ago (used) the 2D transducer did not work. It always read 1.6 feet. In March of 2015 I had it replaced and it worked fine until last weekend.

Now it reads 1.4 foot and the digital readout will not switch to a deeper depth scale. If I'm above 10 feet the 2D and downscan will work but will not switch to a deeper scale when I go deeper. I reset factory defaults to see if that did anything and it did not. I find it hard to believe a transducer will only last 16 months which was about the age of the one I had to replace when I bought the boat.

Any other ideas?

Is the 2d ducer a shoot thru or transom mount?. If it's a shoot thru it could be that epoxy is coming loose. Plug your hdsi ducer straight to the back of the 1198 and make sure everything works, that way you can eliminate the head unit gone bad. Then that will leave you either a bad transducer ,bad y cable, epoxy, or pinched cable

The 2D is a shoot through hull transducer. I was getting a side scan image but not a 2D or downscan depth. From the last time I had this problem, I found that the 2D transducer provides the depth for the downscan function.

Correct. Next time out fill the bilge area with enough water to completely cover the shoot thru ducer. If that fixes the issue then you have a problem with the epoxy. If the problem exists then plug the 2d ducer straight to the 1198( just check the 2d performance) , if this fixes the problem then it's the y cable. After you try those and it still don't work then most likely a transducer issue or pinched cable

Thanks for the information. My boat is out at Bob Sandlin. Next time I'm out there, I'll try this.