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Battery light 2008 rav 4

A few days ago I was driving and the battery light came on. Suddenly the car stopped and would not start. I called my wife and she was able to jump start me but the car would die as soon as the cables were removed. I had the just put a new battery in back in March as it was the factory original and it seemed like it was time.
Anyway I got towed back by my wife and I charged the battery. The car started and held a charge overnight so I thought ok alternator, especially as the car only showed 11 volts across the battery as it was running. I pulled out the alternator and brought it in to the chain got it tested and it showed up as bad. So I bought a new one and put it in
I thought all is right in the world especially as it was reading 13.9v at the battery as it was running.
I took it for a run around the county to test it out but the light came on again! Got home and I am back to 11v.
My question is did I get a bad alternator or is something else amiss? Any ideas would be appreciated

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The year of your vehicle will dictate if the voltage regulation from the alternator is controlled with a separate voltage regulator, or thru the ECU.

Edit: It’s a 2008!

Let me look that up.


Check your battery terminal connections to make sure they are tight,

Voltage control from the generator to the battery is thru Engine Control Module.


Thanks for your info. I am assuming that this is now advanced beyond my skill set. Do you think that the good indie mechanic we usually go to can help or should I call the dealer?

I just did. No luck. I thought well that would be great if I had forgotten

We have had good and bad dealer vs indie reports. I have been to an indie that says go to a dealer, we have heard dealers that are not as good as indies, find a good dealer compare to a good indie, though I think a good analysis by either is probably fine.

My guess is that the replacement alternator has failed. Was this an oem replacement, or aftermarket rebuild? In any event, remove it from the vehicle and have it tested. Many auto parts stores have a fixture to test alternators, or your local auto-electric shop can do this. If it tests ok, you may have an electrical problem elsewhere, for example a communication problem b/t the alternator and the ecm. Or you could just have a burned connector or bad fuse preventing the alternator voltage getting to the battery.

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I took it in to the local mechanic that we use. On the way into town the light went out again. It has remained off ever since. The mechanic looked and could not find anything. I will just keep driving it and hope it stays off

If you are concerned about your battery charge, get yourself an inexpensive battery monitor like this one shown here. You can get them at an auto store or amazon ($10-20). It shows the battery charge with the engine off or with the engine running. Plugs into your cigarette lighter.

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