Intermittent battery light

19963.4lsr5 said:
The biggest pain in the butt for me is pulling the connector out of the back of the Alt.

I also have an amp gauge on my SR5.


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I undid the connection after I had the alternator free from the brackets. Was 100% easier. I have done it both ways and while the alternator is attached to the engine, it took two people to pry it off lol
 
flooredrunner said:
I undid the connection after I had the alternator free from the brackets. Was 100% easier. I have done it both ways and while the alternator is attached to the engine, it took two people to pry it off lol
Click to expand...

Good to know as I’ve heard that’s the most difficult part of the job
 
spartacus said:
You can test the voltage out put of the alternator by checking the battery voltage at idle which should be over 12.4 volts and then reving the engine to 1500 rpms, the voltage should jump up by at least 2 volts. A good charging range is between 13.4 to 14.8.
Also another option, is to take the alternator to a big box auto parts store and have them test it.
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In a correctly operating charging system, the batt voltage should not change with revs, right?
 
If you’re in gear with the brake on idling at 600rpm your Alt is only capable of pushing 40a. Any amp draw over that will cause the battery voltage to drop until the engine goes to a higher rpm.


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I’ll try to keep it short and sweet.

Never had power issues prior and with no changes.
Drove normally Saturday, let sit Sunday, then Monday morning battery light came on 5 minutes down the road, lights dim/stereo turned off/blinkers cut off.

Jumped battery voltage idling around 7-8, same as alternator

New battery/same alternator, idle around 11.9 - 12.1 and 12.2 with engine off; no battery light day of install

Next morning, light back on with same voltages, battery light turned off after 15 minutes of driving, turned off for 9 hours, then light was back on for 5 minutes or so.

Is this signs of a failing alternator?
 
Syndragy said:
I’ll try to keep it short and sweet.

Never had power issues prior and with no changes.
Drove normally Saturday, let sit Sunday, then Monday morning battery light came on 5 minutes down the road, lights dim/stereo turned off/blinkers cut off.

Jumped battery voltage idling around 7-8, same as alternator

New battery/same alternator, idle around 11.9 - 12.1 and 12.2 with engine off; no battery light day of install

Next morning, light back on with same voltages, battery light turned off after 15 minutes of driving, turned off for 9 hours, then light was back on for 5 minutes or so.

Is this signs of a failing alternator?
Click to expand...
Yes, of course. The battery light means the battery voltage is low, not that you have a bad battery. Get a Denso alternator (rebuilt by Denso) or risk a crappy replacement.

Also, you just killed the life of your new battery running it with a bad alternator... get a charger on it and don't leave it discharged like that.

-Charlie
 
3bears said:
I think you need an alternator
Click to expand...

phattyduck said:
Yes, of course. The battery light means the battery voltage is low, not that you have a bad battery. Get a Denso alternator (rebuilt by Denso) or risk a crappy replacement.

Also, you just killed the life of your new battery running it with a bad alternator... get a charger on it and don't leave it discharged like that.

-Charlie
Click to expand...

Ended up needing to rebuild the alternator in the parking lot after work lol. Just replaced the brush and everything was good to go again! Thanks!
QQG1tGO.jpeg
Received the wrong brush, but quick trip to Napa got me home after.
 
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