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Symptoms of Bad Alternator?

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Old 01-24-2007, 03:49 PM   #1
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Symptoms of Bad Alternator?

Recently I have had the follwing symptoms with my 99 4Runner:

1. Running a little rough at idle when the heat/cool fan is on - turn it off and it smooths out.

2. I noticed that my headlights get brighter when I am parked and rev the engine a bit.

3. Windows seem to be rolling down slower than normal.

Does this sound like a bad alternator? I checked the battery voltage about a week ago and it checked out.
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Old 01-24-2007, 04:05 PM   #2
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Originally Posted by Greedy View Post
Recently I have had the follwing symptoms with my 99 4Runner:

1. Running a little rough at idle when the heat/cool fan is on - turn it off and it smooths out.

2. I noticed that my headlights get brighter when I am parked and rev the engine a bit.

3. Windows seem to be rolling down slower than normal.

Does this sound like a bad alternator? I checked the battery voltage about a week ago and it checked out.
What is the voltage on the battery at 800rpm?
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Old 01-26-2007, 09:21 PM   #3
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GENERALY:

A bad alternator will show a DROP in voltage when the engine is reved.

or, in my case, the alternator could go into full fielding, and put out full power. I had 17 volts at about 2000 RPM. Blew both headlights.
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Old 01-26-2007, 09:45 PM   #4
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don't know if this helps, but always check for corroded or frayed wires. That's all i got. I don't own a four runner.
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Old 01-26-2007, 10:02 PM   #5
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Originally Posted by rdharper View Post
What is the voltage on the battery at 800rpm?
...and then at 1800 or so, plus one more measurement with the engine off.


Quote:
Originally Posted by Greedy View Post
Recently I have had the following symptoms with my 99 4Runner:
(hey Gregg!)

It actually sounds like the alternator is fine, given that when you rev the engine you're getting a kick in voltage. That's somewhat normal - though it could be that the low-speed coils are toast. An alternator will have two sets of coils, one for the low RPM and one for the higher RPM. Hmm...

Let us know what the voltage numbers are and we can tell ya' more.
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Old 02-11-2007, 10:55 AM   #6
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Take it to Autozone/Advance Auto Parts and they have a little machine they will wheel out to your car for free to test battery and alternator.
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Old 02-11-2007, 02:53 PM   #7
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You can test it easy by starting truck, then disconnect the + battery lead from battery. If it keeps running, alternator is fine. If you turn on lights, etc. you might have to rev a lil.
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Old 02-12-2007, 09:23 PM   #8
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Quote:
Originally Posted by Greedy View Post
Recently I have had the follwing symptoms with my 99 4Runner:

1. Running a little rough at idle when the heat/cool fan is on - turn it off and it smooths out.

2. I noticed that my headlights get brighter when I am parked and rev the engine a bit.

3. Windows seem to be rolling down slower than normal.

Does this sound like a bad alternator? I checked the battery voltage about a week ago and it checked out.
#2 Happens to my 4Runner all the time. Sympotms started about 3 months ago. Headlights and heater blower power are insanely dim at idle, but since I live in the city where it's bright everywhere, I've mostly ignored it.

I had the oil changed at Mapplewood Toyota here in MN a while back, and they tested the battery and said it was putting out just over 12 volts, and that nothing was wrong with it.

Since that time, the truck has had trouble turning over at least half a dozen times. Mostly occuring after rapid starts and stops while doing errands around town.

My question is, if it's not the battery, and not the alternator (as the stealership told me), what could it be? This is not normal. My previous 2 wheel drive Toyota DL pickup never had electrical issues, and I put more than 200,000 miles on it with the original starter and alternator. By comparison, my 02 Sport only has 77,000 on the odo.

Last edited by spage; 02-12-2007 at 09:24 PM.
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Old 02-12-2007, 09:44 PM   #9
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#2 Happens to my 4Runner all the time. Sympotms started about 3 months ago. Headlights and heater blower power are insanely dim at idle, but since I live in the city where it's bright everywhere, I've mostly ignored it.

I had the oil changed at Mapplewood Toyota here in MN a while back, and they tested the battery and said it was putting out just over 12 volts, and that nothing was wrong with it.

Since that time, the truck has had trouble turning over at least half a dozen times. Mostly occuring after rapid starts and stops while doing errands around town.

My question is, if it's not the battery, and not the alternator (as the stealership told me), what could it be? This is not normal. My previous 2 wheel drive Toyota DL pickup never had electrical issues, and I put more than 200,000 miles on it with the original starter and alternator. By comparison, my 02 Sport only has 77,000 on the odo.
could be your starter if your having trouble getting the motor to fire
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Old 02-12-2007, 09:50 PM   #10
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Thanks, Kyle. Hopefully that isn't the case. It's probably easier (and cheaper) to replace both the battery and alternator, than crawl underneath the rig and yank the starter. It should get me through the winter. Come spring when it's warm I'll investigate further.
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Old 02-12-2012, 08:49 PM   #11
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Hey, I'm sure you've got this figured out already but for others who might stumble across the thread, I found this youtube video on bad alternator symptoms. Looks like it comes from this website here called talk to my mechanic where the help you figure out if you have a bad alternator. Whether or not it pertains to your specific issue with the 4runner, i'm not sure, but its at least a decent resource.
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Old 02-12-2012, 09:03 PM   #12
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4 year old thread.. I hope he's got it figured out by now! LOL

5....

You knew what I meant!

Last edited by chasekerr23; 02-12-2012 at 09:15 PM.
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Old 02-12-2012, 09:05 PM   #13
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5 years old. but yeah seriously.
Check dates people...
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Old 11-06-2012, 02:08 AM   #14
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What if you hear a whistling type of sound? Has anyone had their alternator whistle before it going out on them? It's almost like a belt sound, but it can't be. I just had brand new Bandos installed 3 months ago.
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Old 11-07-2012, 09:40 PM   #15
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You may have a loose belt
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Old 12-19-2012, 08:48 PM   #16
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It could be a bad bearing.
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Old 12-20-2012, 07:38 PM   #17
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more likely
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