coolant light issues!

hi everyone and merry christmas, ino its not the best time but that red flashing light on my dash board is soo annoying and now i wont stop flashing atall! i have tried another sensor and iv tried bridging the wires, that dosent seem to work, however, now i have noticed that when the light is on the selector lights go out when the light is flashing, when the coolant light stops flashing they come back on! wtf! i have had the dash out to replace heater units, but its only started recently! iv put soo much work into this car in the last 3 months, it was a wreck in a field and needed welding, engine rebuild and m.o.ting, its a 1992 classic, iv now started driving it and everything is starting to go wrong, hahahaha! just wondered if there was anymore fuses anywhere or relays that are voltage sensitive or something! Any help would be much appriciated! thanks and merry christmas, Tom.

These coolant level sensors are known for their fickle ways & are often disconnected by owners. You've done the right thing in bridging the wires (as opposed to simply pulling them off) so the only thing that I can think of is a bad earth somewhere. The 'wreck in a field' origin of the vehicle could make this all the more likely. Merry Christmas & a successful 2015 in sorting the beast!

thankyou for your help norseman, the wreck in a field phrase meant that it was laid up for six months and was told it was solid but we all know what lurks benieth dont we!! rot, rot and more rot! but all that is sorted and now its just silly little things! its more of an on going project but i drive her daily! anyways, i checked the volts going into the sensor and it was 12.5! unfortunatly for me when i pulled the tag out the connector it arced on the body and now i have nothing! great! but i have looked in the manuel and found a control box on the back of the clocks, i was thinking that could have something to do with it!? is there a fuse or an earth point that anyone knows of? if anyone has anything that may help please do say! thankyou people, always a help! Tom.