The temp light flashes almost all the time on the 1985 jetta TD I'm fixing up. The gauge itself works properly though! And it is NOT overheating. I've replaced the Coolant bottle and level sensor with no change. I heard about a voltage stabilizer on the cluster. How likely is it that's my issue?
try different cluster... the vs on the pcb on the cluster would make the gas/temp gauges not work at all..
id say its a bad gauge if plugging in a different one solves it..