2001 Cadillac Seville P300 & P306

So I disconnected the cable last night and it didnt work.

I disconnected the battery again over the weekend and shorted the wires and the power door locks, power trunk/gas and moon roof worked. The only problem I have now is just the gas gage jumps around still, when u start the car it will goto half and as you drive it jumps around from half to full. And also I scanned the car and this came up (ABS C1246) and (DDM B1591). I know forsure the rear air shocks are not pumping up but I do hear the compressor kick over everytime I start the car.