I have a 83 280 ZX .With a digital Insterment cluster. My Coolant temp gauge is not working. My Guess is that the sending unit is not working. I see 3 possible units on my engine One at the front of the thermostat housing the others on the passenger side of engine one in the block the other in line with the heater hose Witch one controls the temp gage Thank you very much:classic: :classic: