This just happened yesterday with around 63000 miles on the odometer. I checked the car when I got home and it was charging at 14.8 volts. Seems a little high but I load tested the battery and it was weak which isn't surprising for an original 9 year old battery. I unhooked the old battery for about an hour while I went out and got a replacement. I replaced the battery and took it for a drive. 10 minutes in it chimed and the light came on again. This time I reset all of the fuses in the interior and under hood fuse panels. None seemed out of place but a few under the hood did push in a bit more. Took it out again and 16 minutes in it happened again. Unfortunately I don't have my code scanner at the moment but the battery still shows 12.7 to 12.8 when not running and 14.8 when running/charging.

Is it possible there's a code in there that just needs to be erased (I would assume the battery being unhooked for at least an hour would have cleared any) or does anyone have any other suggestions? I poured through these forums and did other searches but really didn't see much else that could be the cause at the problem - to me the alternator, battery and fuses all appear to be ok. If the light came on instantly I would suspect a fuse or relay but since it takes a while.

I forgot to mention I cleaned up the battery contacts in the hatch and the two at the fuse box in case there was a corrosion issue.

 

Welcome to the site, Try the ground connector at the transmission housing , just to the right of the oil filter cap, is it clean and tight?

 

Have the charging system tested. Most auto parts store have the tester and will do it for free.

 

The "battery light" does not indicate codes. The "check engine light" does indicate codes are present.
The voltages seem right. I wonder if you are confusing the lights? Link to Owner Manual in my sig.

 

I was also thinking the battery cable clamps look for cracks in them , they do fail.


See the crack in this cable clamp?

 

That connection did have quite a bit of corrosion so I cleaned those contacts all up. So far, it's showing around 15 volts still with the light on. I will take it for a test drive now to see how it works. I believe the ECM and BCM control the voltage and it tells the alternator what to put out from what I read - maybe the battery just needs a good charge.

 

Nope I know the lights - just wasn't sure if it would throw a code with the battery light on. Like I said, I have no access to my code scanner so I'm winging it to a certain degree.

 

I checked the battery clamps - they look fine with no cracks. I took it for a drive and the light remains on with the voltage running anywhere from 14.5 to a tick above 15 volts. It still seems high to me but if the new battery is weak (will have to test it as well) it could be causing the alternator to work overtime I assume.

No auto parts stores will check charging systems that I'm aware of in my area but since it's putting out 14 to 15 volts, I don't really see that being an issue.

 

You still need to have the charging system checked with the appropriate tester. Voltage isn't the only thing to be concerned about. Amperage during charging is one thing a tester will check.
FYI. Yes the "voltage" or charge is regulated by the ECM. Depends on the load and system voltage that the computer monitors. The service manual shows a wide range of voltage that the alternator may put out based on the demand. Service manual specs show it could go as high as 19 volts under extreme demand.
Normal range is 14-15 volts.

 

The ground connection in the rad cradle in the transmission side of the rad cradle above the driver’s side headlight


Arrow 2 points to it