Battery light on, battery and alternator seem fine - Toyota Nation Forum : Toyota Car and Truck Forums

Tilland34 · 12-08-2009, 06:04 PM

My starter died the other day. So I just had a new starter and belt installed, but now the battery light is on.

I tested the battery with a meter. It's fully charged when off and reads over 14 V when the car is running.

So the alternator seems to be working and the battery seems to be holding a charge, but the charging light won't go off. Any ideas?

Rip The E Brake · 12-08-2009, 06:46 PM

Remove the negative cable on the battery. If she dies out, replace alternator.

sequoiasoon · 12-08-2009, 06:46 PM

Do you hear any whining noise from the alternator? One of the diodes in the Alternator could be bad so even though you are getting 14V you might not be getting much if any amps. Happened to me in a couple cars. You'd need to get it load tested to see what the output is at idle and at higher rpm.

speedy25 · 12-08-2009, 08:00 PM

Quote:

Originally Posted by Rip The E Brake

Remove the negative cable on the battery. If she dies out, replace alternator.

Sorry buddy but this VERY OLD technique is a recipe for disaster on our newer totally dependent on electronics cars. Yes you may have gotten away with it, but not for long. The original posters method of checking with a meter and finding the 14v is proper.

speedy25 · 12-08-2009, 08:03 PM

Quote:

Originally Posted by Tilland34

So the alternator seems to be working and the battery seems to be holding a charge, but the charging light won't go off. Any ideas?

In the past I had a toyota van with the same problem and the troubleshooting guide mentioned a main relay that wasnt working correctly. When the alternator puts out a charge, its supposed to close that relay and turn out the warning light.

You will have to confirm that with a corolla manual to see if that same technique applies.

Hope this helps.

-SP

Rip The E Brake · 12-08-2009, 08:37 PM

Quote:

Originally Posted by speedy25

Sorry buddy but this VERY OLD technique is a recipe for disaster on our newer totally dependent on electronics cars. Yes you may have gotten away with it, but not for long. The original posters method of checking with a meter and finding the 14v is proper.

Our cars aren't new, and don't really suffer from the issue you speak of....

I've diagnosed 344359834 bad alternators this way... and not had a single other electrical issue besides the usual bad blub...

trife96 · 12-08-2009, 09:26 PM

I know alot of older 7th gens can have some electrical issues. I guess I've been fortunate. But I noticed you said you changed a belt...which belt? I'm thinkin when you said belt, I'm assuming the alternator belt. If so, check your alternator belt tension. Also check the alternator connections and battery connections again.

Tilland34 · 12-09-2009, 10:14 AM

Quote:

Originally Posted by trife96

I know alot of older 7th gens can have some electrical issues. I guess I've been fortunate. But I noticed you said you changed a belt...which belt? I'm thinkin when you said belt, I'm assuming the alternator belt. If so, check your alternator belt tension. Also check the alternator connections and battery connections again.

Yes, it was the alternator belt, it was slipping before my starter died.

I think I'll go and have the system load tested to see what's up.

Tilland34 · 12-09-2009, 03:08 PM

Tested it on a meter, the battery is charging. So I took it by Advance Auto to put it on their load tester. They could only test the battery, not the alternator.

Their box measured the battery at 353 CCA @ 13.02 V. (They tested the battery as a 550 CCA, even though it's a 680.)

Not great I admit, but I didn't think the battery light on the dash lit up when the battery was getting old, only whether the battery was charging or not. (It is.)

I don't want to put a new battery in until I know whether I've got a bad alternator. Someone suggested a diode in the alternator may be bad, how can I test for this?

Thanks

Rip The E Brake · 12-09-2009, 03:28 PM

Pepboys tests alternators.

fast68 · 12-09-2009, 11:36 PM

7th gen do have some electrical issues, i have found out with my 93

includin alternators that can stick and be a constant drain on the battery.

wiring connectors breaking corroding, for charging system

battery clamps factory style very crappy thin easy to break or not tighten up

maske sure are clean dry and tight

replace the clamps with new ones if they wont tighten up all the way

cut off end of cable with tin snips and but a 2 dollar new top post clamp from wherever local auto parts store