Help Diagnosing Battery and/or Alternator Issue - Resolved

[Bluesky 07]

While I was out today, my truck was fine until it wouldn't start. No clicks, no nothing.

Got out the jump box, engine started but immediately died. This happened about 4 times until I tried giving it gas on startup. It then ran fine other than an intermittent whine that was very similar to the noise you sometimes get after a stereo install. Tthis was happening even with the stereo off. No battery light on the dash at any point.

Went by AutoZone and they told me the battery is bad as far as cranking but they can't test the alternator if the battery is bad.

Drove home, where my voltmeter showed 12.6 at the battery with the engine off and a steady 13.7-13.8 with the engine running, but this is what was happening on my in-dash voltmeter. Driving, it occasionally went above 15V. My interpretation is the alternator must need replacement, but could a bad battery cause such fluctuations?

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I have a 3-year-old Toyota battery with a 60-month warranty so in case it was just the battery, I went to Cherokee County Toyota and here's where I need a BS check. The guy reached down and pulled the plug off the side of the alternator and the engine immediately stopped. He said the alternator is almost certainly bad b/c otherwise the engine should keep running.

Can that possibly be true? Besides being counterintuitive, I had researched how to check the alternator at home and nothing I saw mentioned this method.

Thoughts, comments, experience, and theories all welcome.

 

[214RUNNER]

If the battery tasted bad replace it and see what happens if the problem doesn’t change it will most likely be a bad alternator. A bad battery with a bad cell will show it is charging but will die when you go to start it, ? how old is the battery you have in the truck now? Pulling the plug off the battery is not a test check charging cold and hot engine alt will either charge or it won’t charge it is not rocket science.

 

[Seymore Butts]

That's the classic set of bad alternator symptoms.

It sounds like you misunderstood the mechanic. What he demonstrated was a dead battery, which got that way because the alt wasn't charging it anymore.

No way to tell if the battery is a goner as well until you try to fully charge it. BTW, if the battery is defective and you don't replace it, it will take out the new alternator as well.

 

[AuSeeker]

Back in the old days starting the engine and disconnecting the battery was a way to check if the generator or alternator was charging...BUT it's not recommended with more modern vehicles because it can possibly cause damage to some of the electronic components.

That being said I'm surprised the "Tect" resorted to doing that "old school" test when he should have all the test equipment to do it correctly and not cause any further damage!!

But it does sound like the alternator is bad or going bad, i.e. the internal voltage regulator isn't functioning properly, your vehicle should of stayed running with the battery disconnected.

The thing I can't confirm is him disconnecting the alternator instead of the battery would be the same thing, I would think by disconnecting the alternator that would remove the alternator from the electrical circuit, not the battery, but I could be wrong.

 

[inscarguy]

Sounds like your voltage regulator is going bad. If it's at idle or driving the voltage should be at 13.5 - 14 volts. That's what the voltage regulator is for. 15 v and over is too much, that's overcharging. the regulator is in the alternator so it would have to be changed. I would still give the battery a good charge just to be safe.

Good luck.

BTW. pulling the plug off the alt. was an old trick on pre 90's cars, it does not work on newer cars.

 

[Bluesky 07]

Just clarifying, the service advisor pulled the electrical plug off the side of the alternator, he did not disconnect the battery. Don’t know if that’s 6 of one & a half-dozen of the other but just to be clear.

 

[AuSeeker]

Just clarifying, the service advisor pulled the electrical plug off the side of the alternator, he did not disconnect the battery. Don’t know if that’s 6 of one & a half-dozen of the other but just to be clear.

I like stated not sure if it does the same by disconnecting the alternator as it does to disconnect the battery for testing the alternator....but you had the battery tested and it's bad, I'm sure it's bad because the alternator has been overcharging it since you stated your volt meter showed 15+ volts...so even if you just replace the battery the alternator will also damage the new battery... so that being said I would replace them both.

Also just an FYI, disconnecting the battery DOES still work to test the alternator, at least up to about 2011 or so because I have done it on my own vehicles before I heard that it could possibly damage some electronics, then I stopped using that test.

 

[riceandpho]

bad alternator, will cause unstable amperage output also. i had it happen to me with my high output alternator, given the age of parts, i had everything rebuild.

 

[Ventil8]

If it's the original alternator in a 2007, I'd have no problem buying a new OEM alternator. I'm still on my original alternator in a 2005.

 

[Bluesky 07]

If it's the original alternator in a 2007, I'd have no problem buying a new OEM alternator. I'm still on my original alternator in a 2005.

That’s my inclination as well. $313 online through Cobb County Toyota. Reman Denso is $202 at NAPA so essentially it’s a new OEM part for ~$110.

 

[AuSeeker]

That’s my inclination as well. $313 online through Cobb County Toyota. Reman Denso is $202 at NAPA so essentially it’s a new OEM part for ~$110.

I'm having trouble finding the webpage for Cobb County Online parts, keep getting messages either saying "page not available" or "We're coming soon, we're putting the finishing touches on our online parts store...etc. etc."

Do you have a link??

I'd like to check out the alternator you are looking at, at all other Toyota online parts websites it seems all they sell are remanufactured alternators, is the one you're seeing a new or remanufactured(?), what's the part number.

 

[Bluesky 07]

I'm having trouble finding the webpage for Cobb County Online parts, keep getting messages either saying "page not available" or "We're coming soon, we're putting the finishing touches on our online parts store...etc. etc."

Do you have a link??

I'd like to check out the alternator you are looking at, at all other Toyota online parts websites it seems all they sell are remanufactured alternators, is the one you're seeing a new or remanufactured(?), what's the part number.

Wow, good catch, I somehow didn’t realize Toyota sold remans in lieu of new parts. You saved me $110.


Cobb County Toyota

 

[AuSeeker]

Wow, good catch, I somehow didn’t realize Toyota sold remans in lieu of new parts. You saved me $110.


Cobb County Toyota

Thanks, I just wanted to know if it was new or not, if they are selling new alternators for 4th Gens I wanted to get one for mine to have on hand since I have never seen any new ones being sold even from Denso.

Edit: That same one you're looking at is only $215 from McGeorge Toyota.

2003-2009 Toyota 4Runner Alternator Assembly W R 27060-31021-84 | Toyota Parts

 

[Bluesky 07]

Thanks, I just wanted to know if it was new or not, if they are selling new alternators for 4th Gens I wanted to get one for mine to have on hand since I have never seen any new ones being sold even from Denso.

Edit: That same one you're looking at is only $215 from McGeorge Toyota.

2003-2009 Toyota 4Runner Alternator Assembly W R 27060-31021-84 | Toyota Parts

Hmmm…p/n are the same but MSRP is much higher on Cobb County’s site. Weird.

 

[Bluesky 07]

[MENTION=149207]AuSeeker[/MENTION] - Even more weird...I was looking at the part again on Cobb County Toyota's parts site and the MSRP had updated to match McGeorge's. Bought it for $232, which is still less than McGeorge b/c theirs would cost $31 to ship. Plus it's available today.

 

[AuSeeker]

[MENTION=149207]AuSeeker[/MENTION] - Even more weird...I was looking at the part again on Cobb County Toyota's parts site and the MSRP had updated to match McGeorge's. Bought it for $232, which is still less than McGeorge b/c theirs would cost $31 to ship. Plus it's available today.

I'm glad for you I checked at McGeorge before you purchased it, I guess it pays(saves) to check a few different dealers before committing to buy!!

 

[Bluesky 07]

I'm glad for you I checked at McGeorge before you purchased it, I guess it pays(saves) to check a few different dealers before committing to buy!!

Me too, thanks.

I installed the new alternator and have a tip. I typically haven't had issues with stuck bolts so I didn't use PB Blaster before the job. Everything came right out except the 10mm bolt on the lower wire loom bracket. Do NOT round off that bolt!! It's easy to do b/c you can't really get a socket on it due to the tight quarters. I rounded it and had tried everything I could think of with no luck. Fortunately, my wife was out and was able to stop by Harbor Freight and pick up a set of these extractor sockets. With all the other bolts out, I was finally able to wrangle the alternator to a position where I could get the extractor socket on it and break it loose.

My battery was also shot. How shot? On Toyota's machine, my 665 CCA battery tested at 8 CCA. :rofl:

The prorated warranty on my True-2 battery was at in the 50% time frame but they didn't have any, so they offered the TrueStart lifetime battery at 50% off retail, which worked out to $85. That seemed reasonable.

Found some rust under the plastic tray and on the bracket so I painted both with rust reformer and hosed that body area down with Fluid Film for good measure.

Reinstalled the tray and battery and the truck is back on the road.

 

[BlackWorksInc]

Something to clarify here...

I am going to make the educated assumption that the service writer/technican/whoever the OP was talking to unplugged the regulator side of the alternator (3 or 4 pin plug) not the high Amp output cable.

This doesn't really hurt Toyotas as all your doing is inducing a "no charge" condition basically. Theoretically if the vehicle is operating as designed, then the battery would keep the vehicle running until it drops below about 11v or so, at which point the low voltage will start affecting sensor readings and the car will likely stumble and die. Toyota has been pretty good about protecting their electrical systems from stuff like this, I haven't seen too many ECUs or other important modules get taken out often. For something like that, someone would have to be a dumb ass and jump it backwards or bypass fuses.

Unplugging the regulator is also a easy diagnostic method for verifying a bad bearing/abnormal noise in an alternator as the noise will go away or change. It's an old school thing that still works well on most Toyotas. That being said, there is a possibility of causing damage, but realistically that damage would have already been done from the failed alternator and large voltage swings of a dead battery and jump starting.

Just figured I'd clarify that.

 

[Bluesky 07]

Something to clarify here...

I am going to make the educated assumption that the service writer/technican/whoever the OP was talking to unplugged the regulator side of the alternator (3 or 4 pin plug) not the high Amp output cable.

This doesn't really hurt Toyotas as all your doing is inducing a "no charge" condition basically. Theoretically if the vehicle is operating as designed, then the battery would keep the vehicle running until it drops below about 11v or so, at which point the low voltage will start affecting sensor readings and the car will likely stumble and die. Toyota has been pretty good about protecting their electrical systems from stuff like this, I haven't seen too many ECUs or other important modules get taken out often. For something like that, someone would have to be a dumb ass and jump it backwards or bypass fuses.

Unplugging the regulator is also a easy diagnostic method for verifying a bad bearing/abnormal noise in an alternator as the noise will go away or change. It's an old school thing that still works well on most Toyotas. That being said, there is a possibility of causing damage, but realistically that damage would have already been done from the failed alternator and large voltage swings of a dead battery and jump starting.

Just figured I'd clarify that.

This is correct and thanks for the context. I was taken aback as I had never heard of that even after searching the web on ways to test an alternator. I also meant no disrespect and appreciate you clarifying that it wasn’t BS after all.

 

[Rsbhunter]

Aftermarket alt ?

Don't mean to hijack thread, but I'm new here, and don't have 15 replies yet. I just replaced my battery and alternator on my 06 v6 Sport . Went to drive it one morning, batt light was on, and all of the abs, Trac lights...started fine, even drove it 4-5 miles to see if there were any mechanical problems... Any way, battery tested at 11.9, bought new battery...battery light still on.....removed alt, had it tested, bad....ordered a "Remy" alt (rebuilt) and put in. Volts show 12.8 at battery, 14.1-14.2 at idle...Problem, battery light STILL on. Checked all fuses, ign, alt, etc....all good.My obd II reader won't connect (never would) so I'm at a loss? By the way, the speed sensor wire had been pulled apart on the right side ???? I don't even off-road 4 wheel??? Any suggestions on the batt light? Did the batt disconnect, turn on lights, blow horn wait 15 min, etc....still on...rsbhunter