Stop Light on dash and cooling fans

[flyerdave]

Hi, My 406 1.9TD 1997 has had many problems, most of which i have now sorted but there is one that i need some help with from you guys please.

The red stop light on the dash comes on after a short drive and seems to stay on now (use to go out after a while). I have a slight leak on the water fill tank (another job to do) but keep it toped up but i have noticed that even when I let the engine get hot the cooling fans do not activate - the needle on the temp guage is just past the middle of the dial which is when my pervious 406 use to switch on the fans.

Any ideas what may be going on please.