webbysdad- According to my resources, your car (X*** SFC) could have either a 60 or 104 pin EEC-V ECU. I think the fact it may say EEC-IV on the sticker is a bit of a red herring. Your car will be OBD-II, which is what the digital dash is designed for. EEC-IV has no intelligence coming out of it to talk to the dash, never has done!
I'll have to look into it for you. The diagram I have here shows pin 14 on your ECU being the temp gauge signal to the digital dash.
I can verify 100% that ONIS is EEC-IV.