I have a 1980 mercedes 300 SD turbo diesel, and for some reason my car will not start after sitting for 2 or more days. I just got a new battery and that is not the problem. I thought it was the alternator, but I just had it tested at the garage, and it worked fine. I don't know what the problem is yet, but there is a triangle that lights up right next to the fuel gauge everytime I shut the car off. Does anyone know what that triangle means, or what the problem may be???