alternator bad? bad ground maybe?

[1slowgsx]

ok so tonight i was drving and my head unit lost power then it came back on again. then my car starts sputtering and won't acclerate. i'm thinking maybe a bad ground. then my lights get dim along with all my all my interior lights. then my car starts to act very strangely. the warning lights on my dash start cutting in and out. my head uonit totally cuts out. my car studders even worse. then it dies on me. i can't restart it because the batteries dead. me and my friends try push starting it and it barely runs. it sputters and spits out all kinds of smoke. i tried to rev it to get the rpms up and nothing happens. at first i thought i had a bad ground somewhere. now i'm thinking my alternator went out. or maybe both. does anyone have any suggestions on what to look at first. i would really appreciate it.

 

[Defiant]

My guess is with the alternator.

 

[Morphius]

(^^^^) --- I second that.


Using a voltmeter, measure the voltage on the battery. Jump start the car and check the voltage on the car after you jump it. (make sure the j-cables are unhooked.) The voltage should be increasing, if not, time for a new alternator. If it is, you've got other issues.

On a fully charged battery, the voltage should be around 12.6-12.8 volts. While the car is running, the voltage should be around 13.5 volts.

 

[1slowgsx]

would the alternator couse my heead unit and warning lights to cut in and out? or is that something else?

 

[Morphius]

Originally posted by 1slowgsx
would the alternator couse my heead unit and warning lights to cut in and out? or is that something else?

Yes, because the battery voltage is too low.

 

[madaba]

pull the alternator off and take it to a parts store like advance auto or autozone and they can bench test the alternator

 

[1slowgsx]

thanks for the advice. i'm not looking forward to working on my car. no garage and its like 10 degrees outside. im going to freeze my fingers off. damn car

 

[GTM]

Originally posted by 1slowgsx
thanks for the advice. i'm not looking forward to working on my car. no garage and its like 10 degrees outside. im going to freeze my fingers off. damn car

There are a couple of tests with a test light that won't freeze your hands into paws.

With the test light clipped to ground and the key off test the large wire (B+) on the Alt. With the key on probe the the two smaller leads, one will give the same intensity as the B+ (12v) and the other will be much dimmer. With the car runnning again probe the two small wires one will be bright and the other should show very dim or nothing at all. If either of the two wires fail the Alt. will need repair. If the B+ fails then you have an open circuit between the battery and the Alt. which must be found. The test light is the fastest method but if you need output voltage then you must have a meter.

Cheers,
GTM