2010 Tacoma v6- Just replaced alternator and Battery: worked great but now won’t start.

Hey all,

I’m a newish Tacoma owner as I got mine about a year ago used with over 100k miles. The Truck’s been a joy to own and drive.

The Long & Short of it:

5 days ago I was driving and my radio inadvertently shut off and the battery light lit up on my dash. I immediately drove it straight to the nearby Walmart to get a new battery because the truck came with a new 1yr battery when I bought it about this time in 2021. They replaced it and I drove it home, but the battery light was still on after replacing it.

I then went to my neighborhood Autozone the next day on Thursday and had the charging system checked and it showed they couldn’t even read the batteries charge because the alternator wasn’t doing its job. I bought a new alternator and then proceeded to take the old one out and put the new one in. Everything went smoothly and the truck started right up on the second attempt after putting the new one in and connecting everything.

By Saturday, a day and a half later- the battery light came back on again while driving it like normal. I didn’t have the radio on or anything plugged in like my phone etc etc. It became immediately apparent that whenever I accelerated more then 2,000-2,500 rpm’s the battery light on the dash would go out and then come right back on again as soon as I stopped accelerating more then 2,000 rpm’s.

I continued to drive i would normally the rest of Saturday and Sunday because nothing was out of the ordinary. Just the constant battery light that would shut off when accelerating and come back on when I wasn’t. I had zero issues starting my truck or using anything electrical in it.

Today I went to go fill up my truck at the local gas station and it drove fine just like the last 4 days but when I went to restart my truck after putting gas in it started making that clicking noise that sometimes indicates a bad starter possibly. It wouldn’t turn over when I tried to start up the truck. I then had someone come jump me and it started right up when the cables were connected. As soon as we removed the cables though it died and now it won’t even make that clicking noise when I try to start it up again. But all of the electronics are working and nothing is dim or fading. When I turn the key over to just have the electronics turned on everything is now blinking in and out repeatedly. But there’s still power coming from the battery because system light up and it’s possible to charge my phone.

Any and all insight would be massively appreciated because I just don’t have a lot left in the bank at right now. I suspect maybe it’s a connecter or possibly corrosion or something along those lines, but I don’t know and don’t have a lot of experience to draw on.

 

Have you had the New alt tested? New does not mean good sometimes

 

Wires chewed by rodents? Make sure there is no corrosion on the battery terminals.

 

Negative, not yet. Hah! I joined and posted as I was waiting on my tow to arrive. Offhand all I can think of to do is to start retracing the work I did when I put in the new alternator in and checking connections and brackets and everything. I just got it back home and when I try to turn on the power to the truck half the lights won’t come on and the warning lights on the dash are blinking in and out and the radio won’t turn on. It seems like this a bad alternator Situation yeah?

Is there a way to test if it’s the alternator that doesn’t require a volt meter??

 

I don’t see any indications of vermin crawling around or chewing on anything and didn’t when i put the new alternator in 5 days ago. The tow truck driver politely informed me that autozone has a less then stellar rep with new parts apparently. I don’t do enough business with them to say if that’s true or not.

 

yes, test alternator

also, check for corrosion at the ground from the battery to the body, follow the thick black wire from the battery.

it sounds like the circut is intermittently broken. check the connection to the starter as well.

and fuses. there's a big fuse to the alternator that could be blown... it's a fkin pain to disassemble the fuse box and change it

 

Yeah, those rebuilt alternators from the parts shop can be suspect…

In addtion to checking for corrosion at the terminals, have you checked all the ground locations? How rusty is the truck?

Does your Tacoma have any electrical mods that might be draining your system?

All sorts of threads here- search works pretty good!

Good Luck and welcome to Tacomaworld

 

Thank you, I definitely am happy to find and join TacomaWorld! I don’t have any electrical modifications on my truck. I know at the time of purchase nothing was mentioned of any after market modifications made prior.

I figured I probably wasn’t the first guy to have this scenario occur and probably should have tried to search out a related thread before posting :/

It seems like there’s a way to test if it’s the alternator or not without a volt meter/meter tool? I read that if you turn power on to the truck and remove the ground/negative cable from the battery while the power is turned on if the truck dies completely when removed that it indicates it’s a bad alternator. I’m not experienced or arrogant enough to attempt that without checking if that’s a thing.

 

that was on OLLLLDDDDD stuff removing the negative cable..DO NOT DO THAT NOW!! and no, there isnt a way to see if youre getting a proper charge output without a voltmeter. theyre cheap, just get a cheap one and see what the voltage reads at the battery IF you get it started again. edit..also what others have said. I would suspect a bad alternator, however, the truck should still turn over with a good battery as the alternator has zero to do with the start circuit...does it turn over?

 

I think the remove the negative cable while running test might be a bit outdated. It could, mind you could, incur damage in ‘newer’ type vehicles.

I’m sure someone more knowledgeable will jump in.

Can you drive the truck to where you got the alternator and have them check it while it’s in your truck?

In the meantime, maybe invest in one of the jump boxes found at the bottom of this page:
https://www.tacomaworld.com/threads...ds-now-hiring-dont-be-skeert.669927/page-2979

 

One thing to try is to measure the resistance of the wires running from the alternator to the battery. I recently talked to a Taco owner who had a wire with a lot of internal corrosion (which was not visible) which caused the resistance to be very high, significantly impacting current flow.

 

In place of a voltmeter, you can get a USB port with a voltage readout. It may cost the same but you can use the USB port for your gadgets.

Take it back to Autozone, they will check it again at no charge. They wont lie to you if it’s busted. I got an Autozone alt that went bad in eight months. They gave me a new one after checking it. Alt should have a lifetime warranty. But you are on your own for labor.

 

Another thing to add to the list of worries