electrical problem

[TalonTSiDude]

Ok, on the way home from work tonight I was coasting in gear to a stoplight when my battery voltage all of a sudden dropped from 13.4V to 11.7V, all the gauges dimmed, and my e-brake, coolant level, and battery dummy-lights all came on at half brightness (not completely lit up, but somewhat). There was an odd wining sound coming from what seemed to be near the alternator, but I couldn't tell since I was inside the car. When I stopped and popped the hood I could not reproduce the noise, yet the system was still at only 11.7V. When I turn the car off, then put the key in the "on" position, but engine not running, the voltage is at the normal 12.3 and all lights are at full brightness. As soon as the engine is started, the guages imediately dim and the voltage goes to 11.7 again. Anyone have any insights towards this problem? Thanks in advance.

 

[Kevin90GSX]

Yup you need an alternator.

Take yours out and bring it to Advanced Auto and have them check it out. (simple as pie to take out) When I first got my car it would drop and the dash lights would come on till I hit the gas steadily.

And you pretty much proved it is your alternator by putting it in the on position. Since when the car is off and key in the on position you are reading 12v's shows its not the battery but chances are if your alternator is shot your draining the battery everytime you drive around.

Get it fixed asap or be prepared to buy a battery as well.