temperature lamp flashing

I have a 92 Cabriolet with 128k miles. I have done many mechanical repairs.  new water pump,hoses,thermostat,temp sensors,coolant level sensor,coolant level sensor relay, fan sensor, fan relay, head gasket. But I still have a flashing light for the coolant gauge. The light starts flashing when the gauge reaches about half way. The needle never gets  much past the halfway mark before the cooling fan kicks in and brings the temp down. But the light still flashes. Oil pressure is fine,oil level is fine, coolant level is fine, no overheating, belts are tight. Am I missing something ? I'm thinking of just undoing the lamp if I can't figure it out. This has been a problem prior to all this work, I'm at a loss for answers.

might have a problem in the speedo cluster

so after all this work, the light still flashes???  Mine flashes when the fluid is low, but I think that's it.  Sure fluid is good??

Any ideas what to look for in the cluster. Coolant is new.