Common Alternator Problems?

On this 1991 Grand Prix that im getting with the 3.1 v-6, the alternator just went out on it but the oil pressure and gas gauge dont seem to work. The low gas light will stay on, but it will spike as far up as it can go, same as the oil pressure gauge. What could be causing this? If you guys need more information, I will try to provide my best. Thanks Guys

you have a very low battery or a ground problem. Low voltage will cause all kinds of fun electrical gremlins, like guages jumping around. Change the alternator, and see if the problems go away. If they don't, check all your electrical connections for corrosion, especially the battery jump terminal on the drivers side near the strut, they are famous for corroding.