I have a 1998 Pontiac Grand Prix GT. I have been having trouble where I am driving and the car starts to die and then finally shuts off. I jump the car and it only stays on for a few minutes. I replaced the battery with red top Optima @ 960 cranking amps and that didn’t correct it so I replaced the alternator. This morning after I drove the car long enough (about 30 miles), the car died again. It seems as if the alternator is not charging the battery. I have checked the wiring to the battery and alternator and they look good. My next step is to just change the wires anyway because I have no idea what else could cause this. Do you have any suggestions?
If the battery and the alternator are both new and you continually have to jump start the battery when the engine dies…don’t do anything else until you get a proper electrical test done. This is a pretty simple system so I’m guessing it’s something relatively cheap and easy to repair, once you find out what the problem is.
If you have an alternator/starter repair shop in your area I would suggest you take the car to them for testing. This car is not old enough for me to expect you have a wiring problem, but you can ask the alternator shop to make a set of leads that will connect your alternator to your battery directly, thus ruling out the possibility of damaged wiring within the circuit somewhere.
My guess is that you got a defective alternator or you have a loose or dirty connection at the battery cables. An inexpensive electrical test will help determine that.