Intermittent Battery Light

My truck suddenly didn’t start a few times and I needed a jump a month ago. Second time it wouldn’t even start off a jump from a full size truck. Changed battery which was a 4 year old interstate and cleaned all connections. No issues for about a week. Went to start it and heard a weird hum from engine compartment and battery light came on, but it started fine. Battery light went off during the drive and didn’t return for 2-3 weeks (today). Remote started my truck and it shut off then auto Re attempted and started fine but battery light is on again. 3 weeks ago when battery light came on after installing a new battery I had alternator tested at O’Reilly and they said it tested ok and battery tested ok. I’m at a loss now. Not sure if it’s the alternator or someone said my serpentine belt could be causing this. I’m definitely overdue for serpentine belt change and belt does seem to chirp a bit when I start truck rainy days or high humidity mornings. How would belt be the cause?

Any ideas?

Thanks in advance!

 

Maybe the aftermarket remote start is having an issue

Check all frame and engine grounds for corrosion and tightness

Just because the parts store said the alt was fine doesn't mean it is. It could be failing intermittently

 

Check voltages at the battery, and the alternator.

My guess is your alternator is waving the white flag to retire.
If you are going to replace the alternator might as well swap the belt since you gotta un-tension it anyway.

If you want to wrench it yourself. It isn’t too bad to swap the part. I did mine a month ago.

 

Thanks. You did alternator yourself or belt? My pulleys look like shit too, but was hoping to not have to do those as well.

Did you get OEM alternator or aftermarket? I’m kinda done with aftermarket, drums I put on in February rusted already and look almost as bad as 12 year old ones I took off.

 

I did both, I was already in there for the Alternator, and belt so why not?

I went with Alfredo sauce alternator, and whatever belt they had at my local shop.

 

Alfredo sauce alternator? How much did the aftermarket run you? Toyota is quoting me $360 I think. $65 for belt from dealer.

What year is your truck? Thought about doing pulleys also, but they aren’t cheap and I’m inclined to not replace them unless they really need it. They don’t look great on outside pretty rusted, but hopefully the mating surfaces where belt goes is ok.

 

what's the voltage reading at the battery with the engine running?

 

I believe it was 13.6 volts

 

That's an indicator that your alternator is on its way out. You want it reading 14.0-14.5v to indicate a properly working alternator and/or a strong battery.

The current alternator is doing a weak job of charging the battery and some of the truck's accessories are draining the battery down when not in use.

 

Are the aftermarket alternators decent? Dealer is quoting me $325

 

2nd gens don't charge at that high of voltage, mine runs 13.2-14.2 typically depending on temperature. The best on vehicle test is to turn all the loads on (headlights on high, blower on high, etc) and make sure it stays above 13v.

 

Driving home ABS/BRAKE light just came on, LSD light and stereo shut off and won’t turn on. I’d say I have a battery charging problem lmao

 

I’d recommend staying away from aftermarket alternators.
The odds are against you. The likelihood it lasting more than 2 years is low.
Don’t fall for a “Lifetime Warranty”. You might spend a lifetime replacing it, over, and over again.

Walking sucks. Tow bills suck.

 

Look for OEM alternators online from dealers, here is one I've used:

https://parts.olathetoyota.com/

There are several online dealers so shop around and remember delivery fees can add a lot.

 

I believe Denso # 210-1084 - is the number for the 130A alternator for the 4.0

 

I went with Denso as per TNT shooter
I don’t know why autocorrect said afredo sauce.

2007

 

Agreed, 13.6 voltage output is normal for 2nd gen Tacos. The lit battery light can be caused by one of several issues:
loose/dirty alt connections
dirty/loose frame/motor negative battery connections
bad tensioner
weak/bad battery
weak/bad alternator
A bad belt is unlikely unless it is super glazed which would cause slippage.

I would put a plug-in volt meter in a power port and monitor voltage levels as you drive about.

If the truck has over 150K, I would be replacing the alt as preventive maintenance. I did that and kept the oem alt as a backup. I got a BNR alt, they are an eBay vendor. I also got one for daughter’s 07 Corolla. Both have been running well for about five years now.

 

Depends. I don't know much about other brands other than Denso which is OEM. You can sometimes find them cheaper on rock auto or parts geek since they don't use stealership prices.

Rockauto seems to be out of stock but there are plenty of Denso 130Amp Alternators for around $140-$180 before shipping/core on PartsGeek.

 

Never ignore the intermittent battery light!
From my experience, a weak alternator can wear out a battery or vice-versa. I had to replace both after being stranded in the middle of nowhere in the middle of the night.