cn00728

Hello,

Last night as I was on the highway the abs light came on, a min later the battery light came on. The battery light went out and came back on a number of times. I pulled over, checked under the hood, everything looked okay. Really couldn't have been a belt missing because the battery light came on and off. Started the vehicle back up and went the last few miles home. The same lights came on but in the last mile the air bag light came on as well. This is the first ever problem I had with this vehicle in the 40K miles I have owned it for.

This morning I took it to a Toyota dealer to get it looked at and while enroute, the battery light turned on for a second, and then a min. later the abs light was on for the rest of the way. Stopped for gas mid way, and the lights didn't turn on for the rest of the trip to the dealer. 40 min. total trip to dealer.

I told the dealer I was suspecting a voltage regulator, not too familiar with the electrical setup of this vehicle, but I told him that because the lights would get bright at higher rpm's. After they looked at it I got a call that it was the alternator. They said it was outputting around 18v which was over powering the battery. They said it made the battery hot and had some of the acid leak onto the top of the battery, but should be okay.

Now, not to question their decision, but I just don't want to get used by the dealer. I am a loyal Toyota customer. The thing is, wouldn't this be a voltage regulator issue? When they read the voltage output from the alternator, does that really matter? To my understanding the alternator voltage is unregulated, and produces more voltage with more rpms. The only thing electrical really with an alternator are the rectifier diodes, which only change the a/c to d/c. The next component in-line would then be the voltage regulator right? So if that was acting up, then you would be over powering the car.

They didn't have a alternator in stock, but should have one tomorrow.

I don't have a good understanding of this car, or a detailed manual, but does this make sense to someone who knows this truck?

Thank you,
Alex

BOSTON4RUNNER

just like most late model vehicles,,,,isnt the regulator on a Toyota,,,an internal regulator....as in inside the alternator

if I were a betting man,,,,I would say it is indeed the alternator...

my 4 runner hasnt needed an alternator yet, so I am unsure whether the regulator is internal or external...but would bet it is internal

rimpainter.com

Sounds like a bad ALT to me.

Besides, if that does not fix the problem then they were incorrect in their diagnosis, which means you can and should despute the charges and work on the vehicle.

MTL_4runner

Ok, a few things here.

First you need to get yourself a simple multimeter to check the output of the alternator while the truck is running. It is very easy to do, just set the meter to the correct DC range and put one probe on each of the battery poles with the truck running. You should see somewhere in the 14.0-14.5v range (perhaps lower if the battery needs charging). Anything above 15v is abnormal and above 16v is getting into overcharging range.

Next, you are indeed correct that a higher voltage would mean that the voltage regulator went out but as others have already pointed out, it is internal to the alternator. Nowadays almost all the charging circuit is internal to the alternator....this is true for most cars, both import and domestic.

If you are mechanically inclined I would put in the alternator yourself (unless you are still under warranty somehow). You may also need to replace the battery or at least fill up the acid again if you were overcharging it for any long period of time. Keep an eye on it later, it could become a problem.