The temperature light will flash if you have the wrong mix of antifreeze to
water.  Either too much antifreeze or too little will send the wrong signal.
 Also, if the exposed sensor wires are dirty or corroded, the light might
flash inappropriately.  You can do a rough check of engine temperature by
splashing water on the cylinder heads and cylinder water jackets.  If it
sizzles, it's too hot.

Ed