Battery light Indicator?

I just recently got my oil changed at big brand tire… Woke up the next morning to start my truck and the battery light indicator came on my dash… So I pop the hood and check the connections and the alternator belt and everything seems to be fine… Any other suggestions?

 

Did the truck start ok?
Check if the alternator is putting out the voltage it should!

 

^this... The voltage at the battery terminals should be around 12.6 V with the engine off (if not then the battery is not fully charged) and 13.2 to 14.8 V with the engine running @ 2000 rpm (if not the generator/regulator is not behaving properly).

Probably coincidence that it happened after the oil change

 

Thanks guys, going to check the voltage readings when it stops raining and I’ll update this thread... Truck starts fine… But I did notice after starting and stopping the truck about two or three times it started to idle rough, even stalling on the last Attempt...

 

That light came on in my taco Sporadically and then the alternator went a few days later

 

My battery light came on a few days after I was rear ended with pretty significant damage.

Turns out it was only a coincidence. My alternator was going bad.

Let us know after you check the voltage. My money is on the alternator.

 

Bad cell in the battery--how old is it?

 

If the light is on when the truck is running, it means the alternator is going out. The truck runs normally on the alternator when it's running and not the battery unless alternator output voltage drops below battery voltage.

An easy way to see if it is your alternator going out is to start the truck and then disconnect the negative terminal from the battery. If it dies, then it's the alternator.

 

I had just installed a new optima blue when mine went so I just figured it was the alt. Good trick mr burgundy I will rember that’s

 

both the battery light and the parking brake light will come on if the alternator has a problem.

The parking brake light is multifuntion, actually. It reminds you of your parking brake, indicates when you have low brake fluid, indicates if there is a malfunction in the braking system, but it also lights up when the alternator is bad.
At least that is what it does on 4runners, so I guess it's the same with its truck brother, the tacoma

Also, check your fuses, just in case

 

Please don't do that..great way to fry a ecu.

 

Interesting. While this may be true in some vehicles, my tacoma did not show a parking brake light to signal a failing alternator. When my alternator was failing, I only had the battery light illuminated.

 

The battery light can come on independently, but when both are on, then it is 100% sure it is the alternator

 

Good to know. Thanks

 

NEVER! And I REPEAT! Never unplug the battery while the vehicle is running on a newer vehicle! It has the capability of destroying a lot of electrical components!

Running the engine w/out the battery connected, the risk is that the alternator’s voltage and current spikes could damage anything connected to the alternator output, which is pretty much everything, including the car’s computer circuitry and ignition components. All or most of those components have their own capacitors for protection against power spikes, but those capacitors have limits to how much they can take. Without the car battery, its a much iff-ier situation.

 

^^^THIS!!!

I was going to stay out of this discussion, however License2Ill is spot on in this regard--in addition to the filtering action of the battery (which is for all practical purposes a very high capacity capacitor), the generator output is controlled by the regulator, which monitors the battery voltage to determine how much generator output to command. Disconnect the battery and there is nothing for the regulator to monitor. I.e. the generator runs unregulated...

 

That was an easy test in pre ECU days. Like the 60's and maybe deep into the 70's on some marquees.

And while you can try it on an ECU vehicle, you're playing system roulette. Not worth the risk.

Pardon me for piling on to warnings @License2Ill @lucky13don and @cliffyk have already stated.

However, it's important that future readers of this thread ignore this recommendation.

 

I have in the past been chastised as to my use of the term generator rather than the more common term alternator--however the fact is that the engine driven assembly that produces electricity in modern vehicles is a generator, not an alternator.

BUt don't take just my word for it, here's the charging system parts location diagram from the 2nd gen Tacoma FSM:



What happened is that way back when, when wound armature dynamos were replaced with alternators the new device's output was multi-phase (usually 3) AC power that was converted to DC by an external rectifier pack mounted on the firewall, along with the external regulator assembly. I.e. the engine powered rotating thingy, considered as an assembly, output AC electricity and was truly an alternator.

However over the years the rectifiers (and regulator) became incorporated into the engine powered rotating thingy's body, the assembly's output became DC electricity, and the assembly once again became a generator--but use if the term alternator wouldn't die.

Automotive electrical engineers know this and use proper terminology in service manuals and other documents. Magazine writers, most mechanics, and auto parts guys do not know it and improperly call them alternators.


Oddly we call the things used to create AC Power at construction sites, campsites (and homesites after hurricanes) "generators", when in fact they are alternators...

 

ive seen people destroy theyre ecu's on new cars . watched a guy bake a subaru hybrid. then I've seen guys jump the hybrid battery on them, thats a $3000.00 repair. the joys of driving for 3a.

 

no sir, pile on. if you save someone a tow and repair bill its worth it.