2000grandprixgtp1924 
Electrical problems can be hard to diagnose without actually being there.. If you have a good DMM you can pretty much narrow them down. Start off at the source The battery cause batteries sometimes have a weak or even dead cell. Check the voltage of the car without it running in the middle of the battery terminals after you clean them... Then start working out to the end of the connectors you should not even see a voltage drop.. corrosion loose terminals wires etc are the leading cause of most electrical problems and are normally reasons for part failures.. Start the car up turn on the lights to check the alternator 13.8 to 14.2 is approx. what you should see. A good battery will read above 12 volts like 12.5 to 12.8 with a full charge...The good part here is most auto parts places will check parts free but my experience is usually been with loose or corroded wires that give you electrical problems. Below 10 volts and that engine will start doing all kind of weird things ,misfire,shut down etc.
