Join Date: Feb 2013
Location: Aussie in Sweden
Complete stab in the dark but could the green wire be some kind of earth/ground wire? Complete guess but I can't see anywhere/anything that should connect to that green wire and green is commonly the colour of earthing wires?
I am in no way an electrical expert however. Just giving you an idea of something to potentially look at. But as I understand it, as that circuit is not directly powered, the earth/ground cable acts as the negative terminal and if its not grounded sufficiently (or at all), can give somewhat spasmodic signals to the ECU (if any), hence the odd behaviour of the temp gauge? Likewise, if the ECU was getting strange signals it will, as mentioned, run the car rich. Its usually pretty obvious if the car is running rich as you should be able to smell the excess fuel in the exhaust gasses (best not to go inhaling the gas however :P )
Like I said, I could be talking complete tripe (I probably am), but maybe its something to look at? Either way, whoever butchered that wiring sure did a good job!
2000 Alfa 156 Sportwagon 2.0 TS CF3
2002 Alfa GTV 2.0 TS CF3
1983 Porsche 944