The flashing light is an inidcator that = your water level is below the two electrical probes in the coolant expansion tank = (not the refill tank) or the electronics that control this function could have = gone out.  This is a classical problem.  There are many things to try.

1.  check the water level in the = expansion tank.  There should not be any air in the tank, or very = little.  Excessive air may indicate that you have a blown head gasket and that = exhaust is blowing into the cooling system.  This is the worse case = scenario.  Water cools have a bad habit of blowing head gaskets.  It seems = that the wrong kind of antifreeze eats the metal under the head gaskets breaking = the seal.  There is no solution to this except to replace the heads.

2.  check to see if the water = antifreeze ratio is 50%  Some people report that they have solved the problem by establishing the correct ratio.  I personally haven't had any luck = with this fix.

3.  check to see if the o-ring = under the two electrical probes is leaking to the outside and into the connecter plug

4.  check to see if the connection = to the probes is a good electrical connection.

5.  If all of the above are OK, = there are three electrical components which may have become = defective.

    The instrument = voltage stabilizer ( a 10v voltage regulator that is located on the harness = under the instrument panel

    The temp. gauge = integrated circuit which is an integral part of the gauge.  This requires = replacement of the gauge

    The coolant low = level warning control unit is bad.  This is a plug in that on an 84 is located on = the left wall beneath the front dash.

 Hope this helps.  Please let = me know what you find to be the problem.

George 84