Battery light gremlin

[skaughtz]

2007 Camry 2.4L.

The battery light comes on and stays on 19 seconds after starting the car. The car runs fine and everything electrical works, so my guess is that it a bad ground or something somewhere along the circuit.

I know it is not the battery or alternator because I replaced both a while ago and both check out fine with a multimeter. That light could stay on forever for all I really care, but if it is just a matter of tightening or cleaning something, I enjoy fixing things.

Does anyone have any suggestions of where specifically to look? A certain fuse or a ground on the body to check?

 

[Timmastertech]

That is a plain L-terminal alternator. Unplug the 4 wire connector on the alternator and see if the light goes out. If it does the alternator is the issue, the regulator in the alternator is turning the light on.

 

[Kira]

How many miles are on the car?

How long has the battery light been coming on? Since before the battery & alternator was relaced or after?
How long ago is "a while ago"? What quality replacement alternator?

Are you saying the light comes on for 19 seconds then turns off?

 

[skaughtz]

How many miles are on the car?

How long has the battery light been coming on? Since before the battery & alternator was relaced or after?
How long ago is "a while ago"? What quality replacement alternator?

Are you saying the light comes on for 19 seconds then turns off?

It randomly came on about a year and a half ago. First I changed the battery, then the alternator. Still comes on. It comes on 19 seconds after starting the car and then stays on.

 

[Kira]

That 19 seconds part is interesting.
I wonder if some "boost charging" occurs upon startup.....but your circuits are crossed somewhere?
Go to some Camry boards and see if there are common problems with "the main computer" (ECM...whatever it's called in Toyland).

Also, maybe a dirty ground takes 19 seconds to heat up and trigger the light.
You can start by cleaning the terminals of your "big 3" wires. The ground cable at both its ends, the positive at the alternator and battery and frame-to-engine ground.
Remember, corrosion can build up inside swaged ends and go undetected.

 

[mk378]

Looking at the schematic I agree with @Timmastertech it doesn't look like a computer is involved at all. Do the test he said to unplug the 4 wire plug from the alternator the light should stay out. (It also will not charge like that).

 

[charbaby]

Since I read this post yesterday, my hunch is the alternator.
Just a hunch!

 

[skaughtz]

That is a plain L-terminal alternator. Unplug the 4 wire connector on the alternator and see if the light goes out. If it does the alternator is the issue, the regulator in the alternator is turning the light on.

Well thank you, my friend. That solves the mystery. No alternator, no light.

Now, do I replace it or not? Everything is running fine and the voltage checks out fine with a multimeter at both the battery and alternator.

So here is the strange thing... when the original Denso alternator suddenly died on me back in October 2022, I was in a pinch and had to run to AutoZone for a Duralast alternator. When I was experiencing issues back in September 2024 with the battery light coming on after 19 seconds, I took the Duralast out and swapped it for a free replacement at Autozone. Now the second alternator is causing the light to come on as well (it has been on since before and after the swap). I know Duralast alternators are crap compared to Denso, but could it just be something with their construction or wiring that is causing the light to trigger without actually causing an issue?

 

[f355spider]

Can you just get a new voltage regulator? That is probably all you need. Get a good one though...no Chinese crap, which is probably the one in there now. Is this a Nippondenso alternator? If so, get their voltage regulator.

Sorry, just seeing your post directly above. The crap alternator voltage regulator is the issue. My buddy got a "lifetime" alternator from OReily's for his Ford truck. He replaced it every 9 to 10 months and got so frustrated he went to the Ford dealer and got a good rebuilt from them. One and done.

 

[skaughtz]

Can you just get a new voltage regulator? That is probably all you need. Get a good one though...no Chinese crap, which is probably the one in there now. Is this a Nippondenso alternator? If so, get their voltage regulator.

Sorry, just seeing your post directly above. The crap alternator voltage regulator is the issue. My buddy got a "lifetime" alternator from OReily's for his Ford truck. He replaced it every 9 to 10 months and got so frustrated he went to the Ford dealer and got a good rebuilt from them. One and done.

If it is just causing the light to come on then I can live with the light on. She is strictly an A to B car these days. If it is slowly burning up the wiring or something, then I would reluctantly spend the money on a better alternator.

 

[Marcozi]

My suggestion is to check for alternating current (ac) voltage. A friend of mine has an old 300z. He said the electronics were acting flaky. I checked DC voltage at the battery. It was fluctuating. I then switched my meter to ac. Yikes! At times there were ac voltages in excess of 110vac! Turned out the alternator's voltage regulator was bad. He had to replace the alternator as the regulator was available.

 

[incognito_2u]

Just throwing this out there…….
The 2006 Corolla in my sig had intermittent electrical issues that were caused by bad grounds. I meticulously wire brushed, sanded and retightened all the ground points in the engine bay and that did resolve the issue. Not saying that it will resolve your problem, just putting it out there. Good luck.