2014 Tacoma bad alternator, battery or both

I have a 2014 Taco and tonight the interior lights went dim, and the truck needed a jump. The stereo kept restarting on the drive after the jump. It did not throw any kind of lights prior to this. I drove it to Auto Zone and on one volt meter read 13.35 and on another it read 13.3 but said the alternator failed. They told me the OEM battery would not charge. I replaced the battery and everything seems ok. Could the alternator really be bad? Why didn't it throw a light code if it was bad? I don't want to replace the alternator if I don't have to. I'm leaning towards just letting it ride with the new battery. Does anyone have any advice? Thanks in advance.

 

How many miles?

 

42000 miles

 

Ok, so out of warranty (unless you have the extended warranty that covers charging system). Id be more inclined that it was a dead cell. If it ran fine but failed to start- battery (though some of the systems may not function right due to loss of the voltage "buffer" effect). If it died while running- alternator.
Now that you have a new battery, get the alt re-checked. I've gotten false fails from the alt test at Autozone due to battery failures.

 

Thanks for the advice. I was wondering about the accuracy of the Auto Zone voltage tests. How would you recommend to get the alternator rechecked? Back to AutoZone?

 

A simple multimeter. Start the truck, red-pos, black-ground. See what voltage it is putting out.
Autozone will be fine. When I had a bad battery (Optima), their fancy tool kept saying it was the alt until I exchanged the battery and retested.

 

Dead cell in battery will still give you volts but not the amps to start. Happened on my 2009 with similar mileage. Also battery with dead cell will not charge. Alternator is most likely fine. I wish they would go back to amp gauges in trucks. Much more useful to me versus volts.

 

An alternator output test is meaningless if the battery is no good. For this reason, a load test of the battery must ALWAYS be done before the charging system is tested, and any defects corrected. Sounds to me like you had a bad battery, and nothing more.

 

Thanks for the advice guys. So far so good. I guess I'll find out for sure here in the next couple days.

 

Ya I like the idea of a load test first off. Load the battery to half the cca for about 15 seconds if it's a bad battery it will drop off before the 15 seconds is up. You could have a bad rectifier bridge in your alternator. Time will tell though if you keep driving and your truck dies you know your alternator is toast.

 

If you have a sulphated cell you could try trickle charging your dead battery . usually if it's not really bad you can pull the cell back to life just check your electrolyte level first and top it up if the battery is serviceable

 

The battery is a strange creature, some last forever some don't. I had a bosch battery in my 2010 lasted 6 weeks lol I had a battery in my atv lasted 7 years and as you know that's a crazy long time for a little battery like that. the guys above are right good luck let us know how you make out.

 

Buy a $5 dollar DVM at a cheapo tool place like HF.

Measure the voltage across the battery terminals with the truck running. If it's in the 13.5-15v range (depending on how long since you started it) the alternator is likely ok. You can even watch it a few minutes and make sure it doesn't do something weird, like drop out then go back up.

Side note. Does anyone know (@Jimmyh ?) if the voltage regulator is in the alternator or in the ECU, and if in the ECU, what year that may have occured?

 

Traditionally charging systems put out between 13.8 - 14.2v and resting voltage for a 12v lead acid battery that is in good shape should be 12.6v (2.1 per cell x 6 cells). Resting voltage meaning 12-24 hours after receiving a full charge. However, 2nd generation tacos (new autos in general) have a voltage regulator that will vary output voltage between 13.2 and 14.8v based on the ambient temperature and or under-hood air temperature. Higher air temperatures = lower charging voltage to prevent boiling / evaporation of battery electrolyte. Lower or higher than 13.2 - 14.8 and you need a new alternator. DO NOT DISCONNECT THE BATTERY TO TEST ALTERNATOR.

As to milage, it does not mean a whole lot when discussing battery life and performance. Batteries are really only concerned with time and actual usage. Both of which are highly variable and degrade the battery. "Typically" a battery will last 3-5 years with "normal" usage; some last longer and some less. Don't forget that the OEM battery is flooded and requires maintenance. When you change you oil, pop the caps on the battery and check for electrolyte level. ***battery acid + your lack of responsibility = not my problem*** Look in the holes and you will see the electrolyte (hopefully!), the tops of the cells (little fin thingys), and the vent tubes (they look like these () a set of round brackets). The electrolyte should cover the battery cells and be approximately 1/8" below the bottom of the vent tubes. If needed, add DISTILLED water.

 

The regulator is built into the alternator.

 

My battery crapped out on my 14 at 32,000. No sign it was failing. Started fine one minute, dead the next. Same story with Auto Zone tester showing 13+ volts. Dealership gave me a new one since I was under the 36k mark. I said it before, but I think some 14s got a bad batch of batteries.

 

Thanks. Useful to know. Some others marquees are in the ECU, making home diagnosis a bit harder than it used to be, although the alternator itself was a touch simpler.

 

This made me remember working on the old generators with a separate regulator mounted on the firewall.

 

Always fun lifting 40lbs out of the engine bay over fat fenders.

 

Regulators were separate even with alternators early on. At least in my '64 GTO, and I think a couple years after. Not sure what year they went internal. My '59 Apache looked a lot like what you picture. The GTO had a 'sealed' regular, ie the cover had tabs, not screws, not meant to be serviced. Dad was not happy about that. But managed to open and reclose it for a repair anyway

In the 70's I had an 42" cut IH mower (3 blades) with a hydrostatic transmission that was CVT like in nature. With a delco generator. Generator had a split field coil, so it served as the starter and generator combined. 10 hp Kohler motor.