Battery Light Flickering over 3k rpm

[07GOKRT]

Good Afternoon everyone,

I have an issue that I cannot find the answer to anywhere. My battery light flickers at speed of 70 to 75MPH that’s right at 3000rpm. It started doing this about 3 weeks ago. I will list all of the things I have checked and done. Hopefully someone has had this happen and found out the problem.
At 3k rpm the light flickers very faint on the dash. Under 3k no flicker. If I drive 65mph no flicker at 2800 rpm.
1. New alternator about 4 months old.
2. New battery 2 weeks old.
3. New serpentine belt 2 days old no change.
4. Checked Voltage 14.23 when running. I ran wires into the cab and hooked up a digital voltmeter. No change in voltage when light flickered.
5. Checked Voltage when over 3k and light flickering still 14.23 no change in voltage.
6. Checked connections all good. No change.
7. Here is the tricky one. When driving at night with lights on over 3k light flickers. However when I shut my lights off the light flickers more turn them back on and light flickering it ½ the amount of flicking. Note I do that briefly…lol
8. Now when I start the car cold. The motor goes up and down and stutters for about 10 seconds then purrs like a kitten after that.

Thanks
07GOKRT

[06YarisRS]

Good Afternoon everyone,

I have an issue that I cannot find the answer to anywhere. My battery light flickers at speed of 70 to 75MPH that’s right at 3000rpm. It started doing this about 3 weeks ago. I will list all of the things I have checked and done. Hopefully someone has had this happen and found out the problem.
At 3k rpm the light flickers very faint on the dash. Under 3k no flicker. If I drive 65mph no flicker at 2800 rpm.
1. New alternator about 4 months old.
2. New battery 2 weeks old.
3. New serpentine belt 2 days old no change.
4. Checked Voltage 14.23 when running. I ran wires into the cab and hooked up a digital voltmeter. No change in voltage when light flickered.
5. Checked Voltage when over 3k and light flickering still 14.23 no change in voltage.
6. Checked connections all good. No change.
7. Here is the tricky one. When driving at night with lights on over 3k light flickers. However when I shut my lights off the light flickers more turn them back on and light flickering it ½ the amount of flicking. Note I do that briefly…lol
8. Now when I start the car cold. The motor goes up and down and stutters for about 10 seconds then purrs like a kitten after that.

Thanks
07GOKRT

I had a flickering battery light with solid measured voltages and no noticeable effects. I replaced with a reman and the battery light has not illuminated at all. The voltage regulators are known for having issues. Is it possible that your new alternator (reman?) has a faulty voltage regulator?

[07GOKRT]

It could be I got it off Ebay. Said new its depondensa or however you spell it. I was thinking of taking the voltage regulator out of my old one and switching it to the new one. My old one lost winding so I could get lucky with the regulator being good. I just can figure out why the RPM seems to dictate the flickering. that's what stumps me.

[07GOKRT]

06YarisRS,

Did rpm make light flicker more or less? Or did you light flicker random?

[06YarisRS]

06YarisRS,

Did rpm make light flicker more or less? Or did you light flicker random?

No, it flickered from startup and RPM had no effect. It would just blink on and off rapidly but not necessarily uniformly.

Your reman alternator sounds like a Nippon/Denso, which I think is the OEM alternator. I believe there is a vast range in quality of remanufacturers. I always ask which parts they replace. Usually it's bearings, brushes and voltage regulator but that may not always be the case.

[07GOKRT]

Hi All, Glad to say I found the problem so ill pass it on.

I pulled the 5 month old Alt out today and when I spun it I could here a clicking noise. So I grabbed my 7 year old Alt that had intermittent light no charge issue and it didn't make any clicking noise. I thought maybe brush noise. So I pulled the guts off the new alt and put in on the old one put it all back together and BAM no more lights. I checked charging is fine at 14.23. I also found out why the old alt had issue the brushes were so worn they we not hitting the armature.
I found that out when I went to put the new assembly on I had to push the brushes in to get them on the armature. So I looked at the old one they were worn so bad the barley came out of the housing.

Not sure if you can buy brushes only but if you can people might think they got bad alt and it might be brushes only. I will mention I have 324,873 Miles on my Yaris.

Take Care Everyone

[06YarisRS]

Hi All, Glad to say I found the problem so ill pass it on.

I pulled the 5 month old Alt out today and when I spun it I could here a clicking noise. So I grabbed my 7 year old Alt that had intermittent light no charge issue and it didn't make any clicking noise. I thought maybe brush noise. So I pulled the guts off the new alt and put in on the old one put it all back together and BAM no more lights. I checked charging is fine at 14.23. I also found out why the old alt had issue the brushes were so worn they we not hitting the armature.
I found that out when I went to put the new assembly on I had to push the brushes in to get them on the armature. So I looked at the old one they were worn so bad the barley came out of the housing.

Not sure if you can buy brushes only but if you can people might think they got bad alt and it might be brushes only. I will mention I have 324,873 Miles on my Yaris.

Take Care Everyone

Great news! Thanks for the update. Follow up is so important and will no doubt help someone else in the future.

I had torn the alternator from my '06 apart and did think about replacing the voltage regulator, brushes etc but decided to go for a reman instead. It's much more satisfying when you fix a component as opposed to replacing it.