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Lighting and coolant warning problems!

3630 Views 10 Replies 8 Participants Last post by  John Koch
Hi all!

We have a 2000 beetle and occassionaly the blue low coolant temp light comes on (apart from the usual warm up period at startup) even when the car has been running for some time and in mild outside temperatures.

The other "strange happening" is that when idling and cold when the headlights are on, the lights "Dim" for a second or so every 20 or so seconds.

I have measured the voltage when this is happening and there is a distinct drop in voltage as if the alternator drops charging every now and then.

Anyone know why these things are happening??? The dealers are no help at all.

Thanks, Mark.
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The coolant temp sensor is probably bad which is why you get the blue light randomly. It is to the right of the head - where the upper radiator hose comes into the "heart valve". It's like a $6 part and is easy to replace (just be sure to do it with the car bone cold... like after sitting overnight).

No idea on the dimming... sorry. :)
v132z said:
I have similar problem with the coolant temp light. But instead of the solid light,I am getting a flashing bule light. And one time, the tachometer went over 3000 even when the car was in idle!! Any ideas what it might be?
According to Bentley, flashing blue means electrical malfunction (cooling system related). Mine was fixed with aforementioned coolant sensor replacement.

I haven't had any tach gremlins (yet).
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