New alternator, new battery, car still dies.

**m0ng00se** · 04-28-2010

Recently been having a ton of problems with my 98 grand prix GT. The battery light has been turning on and the engine will turn off while i'm driving along with the power-steering.

I replaced the alternator and battery, and its still doing the same thing. It acts fine for 2-3 days, then the battery light will come on and it will die within 30 minutes. The last time this happened, i gave it a jump and it acted like nothing ever happened...

At this point its beyond me. While trying to get home, the car has little to no throttle response. When i press the brakes or even press the window switch, my speedometer will jump up about 5mph. This only happens once the battery light comes on.

Any guesses? Someone suggested the PCM could be going out, but im tired of buying new parts that dont even fix the problem.

Any help is appreciated. Thanks guys

**SDGTP99** · 04-28-2010

At this point its beyond me. While trying to get home, the car has little to no throttle response. When i press the brakes or even press the window switch, my speedometer will jump up about 5mph. This only happens once the battery light comes on.

This makes me think Bad Throttle position Sensor.

**shawngtp** · 04-28-2010

Next time you get the car running see what the output is on the alt. If you are getting 13.8V or higher its not your alt. Then i would look at your batt. Load test it. If the both of them check out to be ok them i would check your pcm. Just my 2 cents.

**Jn2** · 04-28-2010

if your car turns off while driving, than 2 things have to happend, your alternator stop supplying power tot he car, the car than reverts to using battery power(which is when the battery light would turn on), than it runs of the battery, when the battery is drained, the car will shut off...start your car and use a multi meter to check the alternator voltage output...could be a bad cable somewhere, these things to corrode with time...also check to make sure the cables to the alternator and tightened on...

**m0ng00se** · 04-28-2010

Just cleaned off the battery cables of all corrosion before putting in this new battery.

Alternator was tested after my car died the last time, and it checked out just fine. Only thing showing abnormal was the battery(which was to be expected, since it had been completely dead only 45 minutes prior.)

I put the battery one a trickle charger tonight to ensure it is well charged and doesnt strain the alternator tomorrow... Who knows how it will end up though =/

**topswap** · 04-28-2010

Check all of your grounds.

**m0ng00se** · 04-28-2010

Not really sure of all the ground locations. Anyone got links/pics/descriptions? Ill take the dremel to them tomorrow and get a solid connection on all of them.

**machinegunsquid** · 04-28-2010

It may be that the alt. is not providing power to the battery...it happened to mine, still not sure why. I just ran a 0 Gauge wire from the alt to the battery, and it solved it for me.

PS. It was on my GT, not my current car, no idea if it would be different.

**m0ng00se** · 04-28-2010

I think that sounds like a good option machine. Do you think 4 gauge wire would work? I've got plenty extra laying around from my audio projects.

**machinegunsquid** · 04-29-2010

4 gauge should be good as long as it's not a high output amp. I ran 4 gauge to get the length and to see if it would work, and it did, I just wasnt comfortable with that thin of a wire, but then again I try to be cautious. Try it out and see how it goes. You could also do the big 3 if you havent yet.

**Jn2** · 04-29-2010

Alternator not chargig the battery wouldn't cause the car to turn off while engine is running...only time he battery is used is when your using accessories while the engine is off, and when starting he car...once the car is on it gets power from the alternator...you alternator should also have a plug that connects to a pigtail from the wire harness, you could check it aswell...I'm running out of ideas...next time ur battery livh kicks on, unplug the battery, if the car dies than your battery was supplying thepower not the alternator