Possible Alternator Problem

[Rob94]

I noticed that my lights dim and brighten rapidly, either at an idle or at speed. I checked the voltage at the battery, and with the engine running, it is under 12 volts regardless of engine speed. Yet, I am not getting a battery warning light. I suspect, and order an alternator, but am looking for opinions.

 

[sdpatt]

When the engine is running and the alternator is spinning, the voltage at the battery terminals should be at least 13.5V, preferably closer to 13.7V. It does sound like the alternator is not generating the proper output.

 

[Rob94]

Any thoughts as to why the idiot light has not illuminated Scott? That is what is puzzling me. I checked all the connections, and they are clean and tight. The alternator has been ordered and should be in tomorrow afternoon, but I'll still confused as to why the stupid light isn't lighting.

 

[SolidState]

have you checked the condition of the cable from the altenator to the battery?

 

[masho95]

I'm not sure what the exact voltage has to be to illuminate the battery light, but perhaps the voltage is JUST above the point where the light won't come on. Also I've noticed my lights dimming with less RPM's after installing my UDP's. I know this is common knowledge. Do your RPMS drop when the lights dim? You stated that the lights dim rapidly during idle and running speeds, is the fan kicking in droping voltage, I noticed a significant drop when the fan kicks in, or is this a more freqeuent problem?

 

[Rob94]

With engine off, I've got 11.75 volts at the battery. With engine running at 3000 RPM's, I've got 11.75 volts at the battery. The alternator is toast. And yes, I already posted that I checked all the connections, so it's not a cable.

 

[Bizzy]

Maybe your light doesn't come on because it's burned out. Makes sense to me. shrug

 

[JaySHOguy]

Sounds like the alternator is toast
Like someone else said, maybe the voltage isn't low enough to trip the light yet.

Atleast it should come out fairly easily now, eh?
Considering you had it out to replace that wonderful air conditioner line not too long ago

 

[Off Road SHO]

If I remember correctly ( which I seldom do) the threshold voltage is something like 9 or 10 volts.
The light should come on when you turn the key to run with the engine not running.


Tom

<small>[ November 26, 2003, 10:05 AM: Message edited by: Off Road SHO ]</small>

 

[Rob94]

The light DOES come on when the key is on, but the engine is off. I replaced the alternator this afternoon and all is good with the world again. And yes Jay, I've had this P.O.S. apart so many times in the last few months that it took 45 minutes to remove/replace the alternator.