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Discussion Starter · #1 ·
I have an 06 rav 4, 4 cylinder, 4x4 and had a random flashing battery light. After having the battery and alternator checked multiple times at local parts store and they check out I went for a diagnostic at toyota dealer. They found the alternator spiking randomly as high as 15.3. I took the car home and replaced it. I drove it today after having the battery and alt checked again with the new one (reman from orielly) and both in normal range. I went on the highway and my plug in reader was putting alt at any where from 14 to <13.4 volts then going to nothing showing on alt power. Battery stayed at appropriate level the whole time.

I'm lost, what are the chances of getting two bum alternators? I've checked all the wires and no corrosion or loose wires. I had the dealer check for shorts and they showed non. Any ideas or input would be really helpful.
thanks
 

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How old is the battery? check the ground connection to battery and chassis, I had a similar problem on my old car, one of the grounds was cutting out with vibration. changed the ground cable and problem was fixed.
 

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The device your using isn't really an alternator and/or battery tester, it is simply a voltmeter that uses lights to show the voltage instead of a needle.

A good battery will read a little above 12v when the engine is first turned off, and drop to 12v when a load is applied such as the headlights. If the battery is weak, the voltage will drop below 12v is just a few minutes. A good battery will maintain the 12v reading for perhaps 1/2 to 1 hour with the headlights on.

When the engine is started, the alternator should keep the battery at about 13.8 to 14v. If the battery is in poor shape it may be taking more current from the alternator than it is capable of delivering and the voltage will not reach the 13.8-14v. You should consider a defective battery as a possible cause of your problem.

A problem with your technique, is that you are not actually measuring voltage at the battery. Although unlikely, there may be some loose or corroded connections between the battery and cigar lighter which would cause lower readings. Also these LED voltage testers are usually inexpensive, and not always acurate. You may want to verify it is working in another car.

You should really use a voltmeter directly on the cable connectors at the battery. Do not measure the voltage on the battery posts, because the voltage regulator is trying to maintain 13.8-14v at the end of the cables. If you have a loose/dirty connection to the battery, the voltage will be lower on the battery posts.
 

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Discussion Starter · #5 ·
I was using it with the previous alternator as well as in my truck. It seems to be pretty accurate. Well as accurate as it can be for a cheap thing like this! I guess I'm going back to the dealer for another diagnostic to make sure it's working properly.

I do have a voltmeter and have tested the battery. It stays strong when starting and all that jazz. I don't know how to test alt and I'm not very knowledgeable about electronics so I haven't tried that. I did however just get it tested at oriellys for bat, alt, and a load test. It doesn't like to do anything funny until I'm actually driving though. Thanks!
 

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Discussion Starter · #6 ·
I'm going to add a video of what it does on start up. Wouldn't a bad battery show on the tests at auto stores? Also had it in the dealers yesterday and battery tested fine.
 

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They also should check the voltage regulation. On a previous vehicle the techs said that the alternator was overcharging and replaced it, but after a time I had the same symptoms (electrolyte level dropping too quickly, ultimately a failed alternator for the second time) and complained to the dealer's service dept. Then they also checked the regulator and found that it was defective. Unfortunately the cure also called for replacing the alternator again.
 

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Discussion Starter · #10 ·
The alternator has the voltage regulator in it from what I was told. Unless there is another? I took the one that was diagnosed bad back and got a free remanufactured one. I am tempted to just go to napa and buy a brand new alt for 300 and hope it works. As of now I'm only out time and the 100$ for the diagnosis from Toyota. But this is driving me mad. Toyota wanted 820 for a new alt installed.
 

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It doesn't like to do anything funny until I'm actually driving though. Thanks!
That makes it sound like it is caused by a loose connection.

The battery light on the dash derives it's signal from a "battery current sensor". This sensor is located right at the battery post. The light simply indicates that current is not being put into the battery for the purpose of charging.

Of course you already know that one cause of this is that the alternator is defective, but a second cause is that the connection to the battery is bad, or the cable leading to the sensor could be bad. The latter possibilities seem likely due to the intermittent nature of the problem.

To test the alternator, start the engine and measure the voltage at the battery cable terminals (not the battery posts at this time). The voltage should be 13.8 to 14.5 volts. Turn on each of the following, one at a time, and measure the voltage after each change. The voltage may drop slightly as you turn on each device, but if you rev the engine it should return to normal. The headlights, the blower motor, the rear window/mirror heaters.

Now stop the engine, but keep the ignition turned on so that all these devices are still working. The voltage should remain above 11.5 volts for at least 5 minutes.

If these tests give normal results, then your battery and alternator are good, and the problem is likely a loose connection somewhere.
 

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Discussion Starter · #12 ·
I will do that thank you for spelling it out ricki! Electricity makes me a tad nervous. I'll test later this evening when I have another pair of hands and let you know.
 

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Electricity makes me a tad nervous.
No need to worry about getting a shock at these low voltages.

The only word of caution is do not allow any metal object to short out both battery posts together, or allow an object to short the positive battery post to the body of the vehicle. These mistakes would cause severe arcing and possible explosion of the battery.

I have done a little more research and discovered that the output voltage of the alternator can be controlled by the current sensor located on the battery post. You should check that all connections to this sensor are secure.
 

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Discussion Starter · #14 ·
It looks like a malfunctioning control would throw a code. I currently have no codes even when it had a total melt down and I lost steering I didn't get any code but abs vsc.

I will check and recheck all the wires in the morning after I put it back. I ended up pulling the alt again and took it to get tested. It tested 2 times good. I ran out of sun to test the battery.
 

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Discussion Starter · #15 ·
I should also note before this alt I would have this issue only on long drives or really cold weather. This intermittent flash has been going on since the factor alt. I had never had it happen long enough or constant enough to get it to a dealer while malfunction.

My trip from mid Missouri to south Texas last February was awful. This was with stock alt 110k miles. It was below 40 and I noticed it right out of Missouri so I stopped in an auto store. They diagnosed bad battery. Had it replaced, 20 minutes later same thing. I was in the middle of nowhere so I kept trucking to a hotel. In the morning it was much warmer and I made it back no more issues. A few months after I got a solid bat light, alt was bad, replaced it. No now issues for months until a recent 4+ hr trip. Everything else seems to run great.

And I will try to contact the dealer, again tomorrow. I paid them for a diagnosis and I'm still having the same issues after the repair. I would hope they would have seen a bad cable or checked into the easy stuff for what they charge. I'm back at square one. Sorry For the back story/rant.
 

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Discussion Starter · #16 ·
Any idea what this is? It's on the negative and when I tried to check that top nut it's so tight I sure it'll snap before breaking loose. (The black box with the plug in.)

I can't find it on any other pics and auto store didn't know.

Odd note had them test everything again at a different store. Alt, battery, and starter. All passed and on second test I turned on ac and lights before the test was ran. It said starter failed that time.
 

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Any idea what this is? It's on the negative and when I tried to check that top nut it's so tight I sure it'll snap before breaking loose. (The black box with the plug in.)

I can't find it on any other pics and auto store didn't know.

Odd note had them test everything again at a different store. Alt, battery, and starter. All passed and on second test I turned on ac and lights before the test was ran. It said starter failed that time.
Yeah, that's a battery sensor used by the engine computer. As you can see from the photo, some RAV4's don't seem to have it, but mine does.

 

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Yes, that is the current sensor i have been making reference to.

When I say to check the connections on it, I mean both the heavy copper connections plus the multi wire small connector. Anything loose in this component can cause the symptoms you are experiencing.
 

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Discussion Starter · #19 ·
Thank you so much! I was pushing this around and I'm sure my issues are from that. After all that non sense I pushed up on a wire in that cluster and wouldn't you know, no more issue today. I'm going to try and replace or clean all of that area for further reassurance. Thank you so much for all the info. On a side note I can get the alternator out in about 10 minutes flat now. :)
 

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Discussion Starter · #20 ·
Any idea what this is? It's on the negative and when I tried to check that top nut it's so tight I sure it'll snap before breaking loose. (The black box with the plug in.)

I can't find it on any other pics and auto store didn't know.

Odd note had them test everything again at a different store. Alt, battery, and starter. All passed and on second test I turned on ac and lights before the test was ran. It said starter failed that time.
Yeah, that's a battery sensor used by the engine computer. As you can see from the photo, some RAV4's don't seem to have it, but mine does.


June bug, Ricki, any idea where you can buy a replacement for that part? Is it a dealer only part?
 
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