Alternator Issues

I have a 2016 Tundra. It seemed at the time that it was slow cranking. Barely noticeable. I went and had it checked and the diagnostic check revealed a bad battery. I had it checked at three different AutoZone and O'Reilly Auto Parts. The battery was the original and five years old so I replaced it. After the new battery was installed I had them check it again. All three showed a good battery and that the alternator was bad. Not wanting to break down on the road I took it to Toyota and had them check it. They also agreed that the alternator was bad. I had it replaced and just to be safe I took it to O' Reilly's again...19 minutes after leaving Toyota. I had them check it again and again the battery was good and the alternator failed. Can anyone give me some advice on what you think might be happening? It is appreciated.

Respectfully,

Will

 

based on what you are saying, I wouldn't rely on these diagnostic tests! Shouldn't the tests have detected the bad alternator to begin with?

I ask the dealer and do another test there.

 

I'd go back to the dealer and ask who signed off on the work performed........just sayin

 

Thank you! I agree and have already scheduled a follow-up. The Technician told the Service Rep that it is impossible that the alternator is bad...he checked everything and it was working properly...no idea why it would fail after 19 minutes. If anyone has any ideas please let me know what to look for...a knowledgeable friend told me I probably have a loose ground somewhere. For what its worth the truck is cranking and running great...Thanks again!

 

Toyota dealer said my 2000 Tundra alternator tested bad over 100,000 miles ago.

 

Sounds like it didn't fail if your tunny is running great........

 

lol...I had a friend who is a BWW mechanic who told me had the same problem on his...he to has put close to 100K on his. I am thinking I should have left well enough alone...

 

Owning a decent digital multimeter and an Amp clamp is your friend.

 

I think so but any idea on why it keeps failing on the diagnostic tests? Four failures to include the dealership...

 

In old days maybe the regulator ... but I think the regulators have now been integrated into the alternator. Not sure. Either way they should test the whole system at the dealer.

btw, surprised your 2016 battery lasted 6 years. Mine died after 2 years. My Tacoma battery lasted 9-10 years.

 

Who replaced the alternator?

 

I have one...the numbers are 12.48 with everything turned off. With the truck running with the a/c off, the radio/nav off it is running at 13.45...I do not know if that is a problem but I am told that it should be around 14.2 and the service rep at Toyota agreed with me. Any thoughts? Thanks!

 

Centennial Toyota in Las Vegas

 

You are correct about the voltage regulator. I was pleased the battery lasted this long in the Vegas heat...

 

Those voltage numbers aren't too bad. Did you go with lead acid or AGM battery out of curiosity?

 

I had the test ran at four different locations to include Toyota and all four had the alternator fail...two different AutoZones, O'Reillys and the dealership...I am not sure what to do or if I even have a problem.

 

If the new alternator is keeping the new battery charged under a constant load.....you have no problem.

 

Lead acid

 

I specifically asked why my alternator failed the test. Was told it was only putting out 13+ volts but was supposed to be 14+, and that was why the battery went bad. I told em to put in a new battery (battery was 7-8 years old) and we'll see. That 21 y/o alternator is still working just fine.

 

Your voltage values are good.

 

Voltage/current depends on load.

 

It is...I am probably concerned about nothing but cannot find the reason both the original and the new alternator has failed the diagnostic test. And the numbers are the same for the old and new alternator. I just don't want to break down on the road. I plan on driving to Georgia and back from Nevada in the next few months.

 

The bed was empty.

 

The dealer repair tech should have gon a post repair diagnostic check. Take it back and have them run another diagnostic check. They might charge you more $ if it passes...

 

Sounds like you got the same bs diagnosis that I did years agp.

 

You do understand when testing a power supply you have no load and load current checks and regulated voltage checks which has nothing to do with what's in the bed of your truck?

 

Serious?

 

No....ha!

 

When the alternator is truly failing you will notice a lot of strange electrical issues. Examples: Speedometer showing you are going way faster than you really are; using the wipers turns off the AC; random warning light go on and off.. Etc. Just remember, if the alt is bad then it can't replace power to the battery so you are running the truck with a finite amount of energy. Also, a bad alt CAN damage a perfectly good battery.

 

One of my other car voltage is 13.4-13.7v (per design) while running.
i don't recall my Tundra volt gauge ever going above the center line (which is 14V) while running and I think scangauge shows 13.x also. I will have to double check.

regarding my comment about the original diagnostic tests ... If the alternator and the battery were both bad, shouldn't the tests show both failures? Tests showed that the battery is bad and after you changed the battery, the tests showed that alternator is also bad. Maybe your alternator was bad and your battery was ok (good but weak) to begin with?

In general, i am losing confidence in these diagnostic tests unless someone has a good explanation why the alternator failure was not detected to begin with.