alternator problem? please help

[josherino]

so I thinks this is a combination of not having a constant idle of any sort maybe iac, but only at idle my instrument panel becomes noticeably dim (and possibly my headlights, but not sure) the heater when it is on heavily decreases in flow and tone, my really noisey fuel pump completely changes tone. I have a very rough idle too like it doesn't want to stay started and it sometimes dies. My volt meter drops from 14v to 11.7v during this. Also, my vacuum drops an average of 4 psi. Everything goes to normal when i give it gas too. I think that there is more than one thing wrong with my car like ignition, iac, and other things. What confuses me is I thought that when your alternator is going out your battery light comes on? please help, car doesn't like to be at a stop anymore!

 

[femmeDSM]

Sometimes, but not always, you will get the telltale dash lights (usually Battery, Radiator, and one other that escapes me at the moment). What you're describing sounds like a dying alternator to me. You can always check and make sure, though. Get a DVOM and check voltage at the battery with the car off. Should be right around 12v. If it's much lower, you'll need to replace or charge the battery.
Then, have a friend start the car. The battery voltage should now read approx. 14v.
Turn on all available accessories, (i.e. put the electrical system under load) and the voltage should not drop much below 12.5 volts or so.

Anything lower than those numbers, and the alternator is likely toast

Check the alternator belt, to make sure it's not loose, and check the crank pulley to make sure it's in good condition, and is not slipping.

Edit: Also, thought I would mention this, just in case.
Try thoroughly cleaning and tightening your battery cables, and cleaning the battery posts. Sometimes they can start to ground out, or get bad connections and put a major draw on your electrical system (sometimes causing the car to die, etc).

 

[DSMcamaro]

Edit: Also, thought I would mention this, just in case.
Try thoroughly cleaning and tightening your battery cables, and cleaning the battery posts. Sometimes they can start to ground out, or get bad connections and put a major draw on your electrical system (sometimes causing the car to die, etc).

I was just going to say that. The headlights on my old buick would get brighter when i stepped on the gas becuase of the combination of a bad/loose ground and the alternator starting to go. Check your battery cables, real easy thing to do.

 

[femmeDSM]

I was just going to say that. The headlights on my old buick would get brighter when i stepped on the gas becuase of the combination of a bad/loose ground and the alternator starting to go. Check your battery cables, real easy thing to do.

Yeah.
Besides, on cars as old as ours, it's not a bad idea to replace the battery terminals and/or cables anyway....I know it's near the top of my "To Do" list at the moment....

 

[josherino]

where can you get the battery terminals? are they universal?

 

[talon212]

you can get battery terminals at most auto parts store.

 

[femmeDSM]

Yeah, I think I even saw them at Walmart....Although I would hesitate to purchase any auto part from WalMart.....haha. But you can find the terminals anywhere

 

[Sinclair159]

A good battery voltage will actually read around 12.6v anything under that i would be concerned about.. check your battery then go to your alternator... if your charging system is operating properly under load, it should never drop below .5v's over base voltage...