I can('t) believe I'm having another problem.

[Benag]

I think this time my alternator has gone out. I'm taking it to autozone for testing tomorrow I just wanted to post some symptoms and see if you guys think it's the alternator.

• About a week ago when I turned on my lights after driving (I'm parked) everything went dim. It still runs fine though.

• Week later I try to start it and it won't start so I jump it but it still won't, only turns over reaallly slow.

• These two things I only noticed after having driven it for a while.

• I finally drive it home after roll starting it in 2nd (how bad is this method?) and notice how much power is sucked when turning on the brights.

Now does all this sound like a bad alternator?

 

[GSX6bolt]

This happened to me exactly...

Could be 1 of 2 things....

Alternator, which it most casees your alternator will either blow, or not blow.

Check your volts on your battery... Check for battery acid around the + and - connectors..

You most likley have a bad battery....



My battery was shot... I could jump it and roll start it, but everytime I turned it off, I would need to RE jump it... I would actually turn on the radio, and the car would die. Was a bad battery....

Give it a test.

 

[luv2rallye]

Could be battery or alternator or 100A alternator fusible link (check this first).

If the voltage on the battery is above 13.9V when engine above idle (2500 rpm), it means the alternator is putting out but the battery is not holding the charge - so bad battery. If below 13.9V (or even below 12.5), the alternator is not putting out - so bad alternator. That is one case. Another possible case of being below 13.9V, however, is when the battery has a short (or dead cell) within it which causes the alternator to put out max current but because of the short, the voltage drops - so bad battery (and alternator is actually ok). This is the case when if you now turn the engine off and the headlights on, they are dim and battery voltage is below 10.5V. When everything is running properly you should have around 14.4v on the battery at 2500 rpm.

Simple test: Measure battery voltage with engine off and headlights on (should be >11.5V) and then headlights off (should be >12.0V). Then measure battery voltage with engine running and headlights on and then off (both should be >13.9V).

Another simple test:
(Warning: This test may cause a voltage spike which could damage sensitive electronic equipment including the ECU - although the ECU is supposed to be protected from this)
1) Turn off/disconnect all sensitive electronic equipment like radio, amp, radar, GPS, etc.
2) Start car
3) Disconnect battery positive terminal (Note: this may cause a voltage spike thus turn off/disconnect sensitive equipment first)
If your car shuts off, your alt. is shot. If it stays running, it's the battery. Car should run with the battery disconnected if the alt. is good.