Coolant light problem

At 80,000 miles I had the dealer replace the timing belt and water pump on my 2002 NB 1.8 turbo. Now I have what may be a related problem. We have been having typical weather here, but normally on the cold side. The red temp indicator light comes on with the ignition as always, then turns blue when the engine starts as expected. After several miles, when the engine is at temp, the light goes out, again just as it should. After a few minutes, it comes back on in blue and stays on at about half brilliance continuously. If I shut the engine off at a light, it repeats the entire cycle as above, except that the light is at half brilliance blue immediately after the engine starts. The only time it is off completely after the engine has run is following a normal warmup cycle.

I believe this may have some influence on the engine control computer, so any advice will be appreciated--the dealer will get a call Monday.

Thanks

Sounds like the coolant temp sensor although with the blue light at halfbrilliance you'd reckon something had a bad earth or a bad connection somewhere. I'd try all sorts of variations when this happens like headlights on/off - heater/aircon on/off etc with all electrical thingos and see if that affects this blue light.....if one of them does then it might give a clue.