My stang has 156k miles and has an amp and subwoofer box. I noticed the other night when i put it in neutral to coast to a stop that the battery light comes on. But when i start moving or start revving the engine up the light goes away. Is my alternator going bad?
did this just start? did you have the sub before? many parts stores will check the charging system out for ya for free. battery should show ~12.6 volts when the car is off. should be around 14.5 volts at 2K rpm.
do the symptoms change if you dont have the stereo on?
good luck.
Use theses sites for information on the right way to do the wiring. Some people will tell you that you can skip the wiring upgrade, but it will catch up with you sooner or later. A fire in the wiring harness is ugly and expensive.
Under no circumstances connect the two 10 gauge black/white wires to the 3G alternator. If the fuse blows in the 4 gauge wire, the two 10 gauge wires will be overloaded to the point of catching fire and burning up the wiring harness.
Electric fan = 3G alternator if you want long life & reliability from your car.
Figure this:
Ignition system & computer = 12 amps
Fuel pump = 12 amps
Exterior lights = 15 amps
Fan (heater or A/C) = 15 amps (can run between 5-25 amps depending on setting)
Radio & instruments = 10 amps
Wipers = 10 amps
That's grand total of 74 amps from a 65 amp alternator. Talk about overdrawn at the bank!
Under no circumstances connect the two 10 gauge black/white wires to the 3G alternator. If the fuse blows in the 4 gauge wire, the two 10 gauge wires will be overloaded to the point of catching fire and burning up the wiring harness.