(Over)Charging Issue on 2010 Taco

Good morning!

I hope everyone is well and is ready for a long weekend. I have an (over)charging issue that I am hoping someone may have had a similar experience with.

I have been searching through the forum with little success on finding, so apologies in advance if I have overlooked. I have also done some generic google'ing on the issue.

Problem:
When running, alternator output is almost 16v. Battery is at 12.6(ish) at rest.

My thinking is this is indicative of a voltage regulator problem and should be addressed rather quickly. My understanding is that for a Gen2 Taco that the regulator is built-in to the alternator.

Has anyone experienced anything similar that could offer some guidance?

I'm not adverse to taking anything to a dealer when necessary, but I am capable of doing a large amount of work on my own.

Thank you in advance for any contributions!

 

Are you the original owner? it's a complete long shot, but maybe a previous owner installed a voltage booster in your fuse box. I have one in mine to up the charging voltage for an AGM battery. The old versions had a device with dip switches and you could set how much increase you wanted. I'm sure something like that could fail. Mine just looks like a regular tiny little fuse with no adjustment.




I just found this picture of a homemade one. Mine literally looks just like the 7.5amp fuse, it didn't need all the add on stuff with the resistors as it's all built within the fuse. From my understanding, this fuse tells the ECU how much voltage the alternator is making, and if it's not enough the ECU tells the Smart Alternator to up the voltage. The resistor lowers the voltage output to the ECU, so it thinks the alternator is putting out less than it is thus cranking up beyond the normal stock output.




Again, total long shot...

 

YF_Ryan, thanks for the idea! It was definitely worth looking at before getting an alternator and swapping.

To me, the fuse looks just like the stock one... I didn't see anything to lead me to believe that it is 'smart' in any way.

(Attaching a picture of the block. Did not snap one of the fuse, but I did remove it and visually inspect.)

 

Not that you need this, but if you ever buy an AGM, here's what I bought. They sell them on Ebay for US customers. Made a big difference on resting voltage and getting my batteries fully charged.

https://www.hkbelect.com/product/182-75a-mk2-micro-bladelow-profile-electronic-fuse-version-2011/


Good luck with the alternator! They're a pain to swap for someone not too mechanically inclined like myself, but with an extra set of hands and a step by step guide here on TW, I managed in a shell station parking lot, lol.

 

15.8v at idle is high.

I'd be curious to see what your readings are 2,000 rpm.

 

TnShooter. I've seen as high as 6.1... I went ahead and pulled the alternator and about to go and exchange and see what the result is.

 

Try to get a Denso if you can.
Anything else is a 50/50 chance it will last 1 year.
And a 10% chance it wont work right out of the box.

 

Just got it swapped out. Unfortunately... no Denso, so taking my chances.

At idle, it is now 5.1-5.2

At 2k RPM it is 5.4

 

You mean 15 not 5 right?
That's still high, should be in the 13.2-14.8v range.

I think I'd check the voltage at the S-Terminal (Pin 1 (White)) of the alternator connector, it should equal battery voltage.

 

If it really is still 15+ volts, I’d suspect a bad meter

What’s it read with the engine off, OP?

 

That's certainly possible, if the Sense (Alt-S) circuit has high resistance where the alternator "sees" a lower than actual battery voltage it will increase it's voltage output to bring it up.
That's essentially how the "voltage boosters" work by dropping the voltage to the sense terminal of the alternator to make it output a higher voltage.

 

Whoops! 15... yes.

 

They aren't internally regulated to a maximum output voltage?
You'd think they would cut out at a certain voltage?

 

I will take this as a

I am sure that the experienced already know this... but always... ALWAYS... put a second meter on it (before spending $$$).

Once I got 2 different readings I borrowed a third meter from my neighbor to confirm which was accurate. Aaah, life lessons.

Now to remove the alternator and put the original back on

 

Ouch... I've definitely swapped parts that didn't need it before... but that was a lot of work/money compared to my mess ups. Least you figured it out!!

 

I can't say I've ever changed an alternator out that was over charging.
They've always under charged, or didn't charge at all.
But I don't do this stuff for a living. And I rarely ever check an alternator.
I'm in the 99% that drives it, until there is a problem.....

 

At least they will take it back... I look at is practice for game day at this point

 

How many miles on your original alternator? might be worth keeping for the inevitable, lol. Mine made it about 100K/10years.

 

Assuming it is original (150k)... you might be on to something...

 

Same, never had an overcharging issue (and still haven't). Might have gotten a bit spooked at some of the warnings on the web about it, so wanted to play it safe.