I had the same symptom with my 898 recently. No DI, SI or Sonar, only GPS. Took me a month of asking and trying different things, then finally I woke up in the middle of the night and realized that I updated to newer software version, (which I have done many times) and forgot to delete the previous update file from my SD card...........OPERATOR ERROR!!! Deleted the older update off the card and everything started working again!