Nearly broke down, dead battery or alternator.

Limped back home barley.

Im wondering if my battery or alternator is toast, or both. Any advice would be great.

My experience is that being a dead battery, the alternator should still provide electrical power right?

TLDR
Broke down on the highway with a dead battery and a suspected dying alternator. Managed to limp back home……just.

Symptoms:
Needed the jump leads or battery jumper, Dim interior lights, slow windshield wipers, battery light on, ABS light on, parking break light on, unable to use ext lights.
Barley able to accelerate past around 800rpm, back firing

Troubleshooting:
Loose Battery terminal - Check
Drive belt - Check, not loose or worn.
Fuses - ?? There a alternator fuse?
Alternator Cable to battery - looks plugged in.
Battery Voltage - 10.5v and declining.
Parasitic voltage draw - Unpluged EVERYTHING

The story:
I started the truck just fine on the way out to work. A bit later the battery light when on, I stoped and verified that my battery is at 10v with the OBD2 and cig volt meter.
Having dealt with dead batteries before, I knew that as long as the engine is turning the alternator is providing electricity. So I set off anyway.

Then things deteriorated rapidly, all the instrument lights were a lot dimmer than normal, the wipers were slow and sluggish the head lights were dim as well.
I was about to be on the on ramp when I noticed that I could not get any more RPM. It just chugged, and refused until I eased off the pedal. I had to pull over on the highway.

I pulled over and connected the portable battery that I use for jump starting. Then all the lights were normal, but not the battery voltage. I refused to turn off the truck. And did the trouble shooting with what limited time I had.

So I raced/limped back home with no lights, no turn signal, no speedo it was freaking out, and a rain soaked and fogging up windshield I just managed to limp back home as it was already backfiring/ running rich, and complaining or close to dying 100ft away from the house.

 

What voltage do you get when you measure across the battery terminals while the engine is running? You should be getting 14.0-14.2 volts more or less. If not then you need to look at your voltage regulator which is usually a non replaceable part of the alternator. Your battery should be at 12.8 to about 13.2 with the engine off, but your alternator needs to be actually charging the battery and your battery needs to be fully charged before you make any measurements. So there could be a couple of things going on here. The first thing you need to do is make sure your alternator/voltage regulator is putting out enough volts to charge the battery. Then you need to determine if the battery itself can be charged and hold that charge. And remember that you always need higher voltage going in to the battery than coming out for the battery to charge. You very well might need both an alternator and a new battery as well.

 

Pull the battery out, take to a parts house and have load tested.

Start simple.

 

If it started fine, then while while driving down the road the charge light came on, while still running, then got worse and worse to the point interior lights dimmed and the engine misfired, you need a alternator.

 

@Sasquatchian,

Yes I noticed that my battery volt meter usually reads 13v or 14v this thing that’s attached.


okay so check the cables from alternator to battery

@Clearwater Bill, normally I’d agree with it’s probably the battery. But a total electrical loss/discharge while the engine & alternator is running is suspect.
Ive driven around with a dead battery before, just don’t turn it off.
I don’t want to just throw parts and Labor at the problem only for it to be a simple fix.


@wrightme43, I’m 70% certain it’s the alternator. I’m just hoping it isn’t as a battery is a very easy fix and is by best case scenario.
As mentioned to the other member, Ive driven driving with a dead battery isn’t an issue as long as you don’t turn the engine off. Had tho drive like that many times but never had something happen to me like this.

Were all electrical components and the engine started slowing fading into the darkness.

 

What would be the part number for a 07 Tacoma alternator that has the towing package.
I’m assuming it’s different than the “normal” ones

 

You can usually get them from a parts house for about the same since rock auto charges shipping.

 

I am certain it is the alternator. Either the ignitor signal to the alternator, or cable from the alternator to the battery, but the odds of those are miniscule. Unless you have been playing around with wiring it will be the alternator.

 

and many times they'll have a core charge, so it can be even cheaper.

 

The only thing that comes to mind is the any time 400w inverter mod.

 

With a jump start I’m only reading 10v not the normal 13-14v
Battery with engine off was at 10v now is at 6v.

 

Yes sir. You need a alternator.

 

If only there was an alternate solution to be found.



too soon?….. yeah too soon

 

Echoing the same. Just went through the similar thing with my '10. 4 cylinder but the alternator wasn't terrible to change, about 2 hours and that's shooting the shit with my dad while doing so. Flexible ratchets will be your BFF for the job, grab a 3/8 and 1/4 at Harbor Freight if you don't have already.

 

Changed the alternator with a Denso 130amp remanufactured.
Only cost me CAD $300.00, 2 Horus, and 2 beers.

Getting 12.9v while charging a flat battery. I’m sure I’ll get 13.5 when it’s charged.

Eat that Toyota Langley! $1,150.00 my asssssssss

 

Mine ran about 300 USD for an OEM and about the 2 hours, minus 2 beers for me.

Had I not had the garage to work in at my parents' house I might have called my independent guy.

 

Langley Toyota not today