Dead battery or alternator?

[fuzzybabybunny]

I've got a 2006 Toyota Yaris with about 70,000 miles.

Up to this point it has been acting completely fine. All electrical systems work wonderfully. Starts are nice and quick.

This morning I go back to the car and nothing works. Power door locks don't work. Interior lights don't work. The headlights and interior lights were all in the off position. No sounds come after turning the key.

I had someone jump me and the car started up with a slight hiccup.

I left the car idling for five minutes and noticed that the interior lights were flashing. If I press the gas the lights become constant.

I used a multimeter to check the battery at the terminals and the voltage fluctuated between 12.7V and 13.1V.

I went to go drive the car around after seven minutes of idling. Manual transmission. Put it into reverse. Reversed a bit. Then it just shut off completely when I went to put it into first with the clutch still pressed in.

Ummmm... I'm not sure what's going on here. I want to say that it's the alternator, because I don't think batteries fail so suddenly (overnight). There also might be corrosion around the battery terminals but again I don't know why that would contribute to such a sudden failure.

 

[michal1980]

could be both.

But batteries can die that quickly:
Went to lunch with my friend, car started fine when we drove there. 40 mins later car wouldn't start. battery had a lot of corrosion on it, I think it was the original battery and it just happen to die then.

 

[LTC8K6]

Well, the voltage reading should be above 14 with the engine running, so that points to the alternator.

If it's the original battery, then it's time to replace that anyway.

 

[fuzzybabybunny]

I'm standing outside the car now. I cleaned the terminals and the clamps. There was some corrosion.

It's idling and the voltage is reading ~13.6V. Definitely not 14V.

Even when idling, my instrument panel is flickering. Fuhhhh alternator?

 

[fuzzybabybunny]

When I initially jumped the car the engine started but then made a quick weird sound. Then started up. There aren't any warning lights on the dash about the electrical system.

 

[fuzzybabybunny]

It's only idling at 500rpms too. When I press the gas to 1.1k RPMs the flicker on the instrument panel goes away.

 

[michal1980]

low idle would cause the dash to flicker.

when the car died the idle control valve might now need to relearn position. And is probably dirty.

see this video

https://www.youtube.com/watch?v=mGs0j5FT220

 

[LTC8K6]

I'm standing outside the car now. I cleaned the terminals and the clamps. There was some corrosion.

It's idling and the voltage is reading ~13.6V. Definitely not 14V.

Even when idling, my instrument panel is flickering. Fuhhhh alternator?

Might have lost a diode in the alternator.

What is the voltage with the engine running and the headlights on?

 

[fuzzybabybunny]

Might have lost a diode in the alternator.

What is the voltage with the engine running and the headlights on?

13.42V with headlights on.
13.52V with headlights off.
13.28V with headlights off and AC on.

 

[LTC8K6]

Now what is the battery voltage with the engine off and the headlights on?

 

[fuzzybabybunny]

now what is the battery voltage with the engine off and the headlights on?

12.32v

 

[fuzzybabybunny]

12.73V with the headlights off, engine off.

 

[pcgeek11]

I have 3 Toyota's and none of them charge above 13.8 volts when running. Even when new.

OP I would place that battery on a slow charge over night and then look for a parasitic drain.

 

[LTC8K6]

Yeah, originally 12.7-13.1 while idling sounded like the alternator, but 13.6 is better.

If it's the original battery, I would replace that first and see if the problem is solved. If it hasn't failed yet, it will soon.

 

[eng2d2]

I would start with the battery first. You could also have autozone or oreillys check it for free.

 

[sontakke]

Come on replace the battery first before even *thinking* about the alternator! The battery is old and can die with no warning. If new battery still gives you the same problem, then start diagnosing it further. Until then, don't do any "what if" in your head!

 

[Torn Mind]

I am suspecting alternator, and possibly more than one part in it. Diodes might have died(flashing lights, yeah), and maybe even the rotor itself; although the voltage regulator could be the failed item causing these lower voltages.

Check the diodes and slip rings in the alternator. There should be VERY low AC voltage at the battery terminals. Even .1 V or something is too much. The more thorough diode test involves checking the assembly inside and seeing if there is continuity one way and none the other way. There "core" of their alternator hasn't changed much at all over the years, just the connector locations.

Toyotas likely need an 8, 10, and 12 mm socket/wrench/nut driver and Phillips screwdriver to open up the alternator.

http://workshop-manuals.com/toyota/...ernator/component_information/specifications/

To be absolutely sure, you should pull the throttle cable and check your alternator voltage. At 2000 rpm, the manual specs say the voltage should be between 13.2-14.8 volts.

Diode assemblies can be replaced individually for less than a remanufactured alternator, although if the alternator is old enough, the corrosion on the screws might cause them to strip.

Pressing the throttle should keep the engine running even with a dead battery at 0 volts because the alternator should definitely generate enough power when spinning faster. It's releasing the throttle with a battery at 0 volts that should cause the car to stop completely.

 

[Kenmitch]

Come on replace the battery first before even *thinking* about the alternator! The battery is old and can die with no warning. If new battery still gives you the same problem, then start diagnosing it further. Until then, don't do any "what if" in your head!

Yep.

Idle issues are the norm for old dirty Toyota throttle bodies. Pretty much just have to carefully clean the throttle body and it should idle fine. It's a drive by wire setup it looks like so you don't want to force it open when cleaning it. Just do key on engine off and place something on the gas pedal or have somebody hold it down to open it.

 

[z1ggy]

Come on replace the battery first before even *thinking* about the alternator! The battery is old and can die with no warning. If new battery still gives you the same problem, then start diagnosing it further. Until then, don't do any "what if" in your head!

This. Process of elimination. Although, putting in a new battery and having the car turn over and start doesn't 100% rule out a bad alternator system.

 

[Torn Mind]

Some Toyotas cannot run with a battery at 0 volts. That's what sounds like happened. Everything's rosy, but the a diode suddenly died, causing the battery to drain overnight to the point even the dash lights cannot come on.

I have experience dying batteries, and those with charge but cannot start the car still operate lights and the electronics. If those things fail, then something caused it to drain to 0 volts or close enough.

All this guy needs to do is check AC volts on his alternator first before buying a battery and risk damaging his new 100+ dollar battery.

 

[tortillasoup]

13.42V with headlights on.
13.52V with headlights off.
13.28V with headlights off and AC on.

your alternator is fine. take the battery to some place like autozone and have them charge it. you'll burn out the alternator trying to charge a severely discharged battery.


on second thought, charge the battery either with own charger or an autoparts store charging it. install battery and if you experience the same issue with the flickering, then bad alternator.

 

[sontakke]

It is a bloody 2007 battery, replace it without giving a second thought.

Personally, if the battery is over 3 years old and I have *any* electrical issue, I replace the battery first before even taking out my PowerProbe or multimeter (just a little exaggeration). But if anybody calls me for advice, I am sticking to it.

Same story when somebody tells me "how come both headlight stopped working at the same time? I must have big electrical problem with my car" - No dummy, one headlight died some time ago but you did not notice until the other one died.

 

[fuzzybabybunny]

Took the battery in to get tested and the battery failed. So it was the battery that was the issue. It's not the original battery either - I bought the car used and it already had a 3rd party battery in it. Thanks all! Glad it wasn't the alternator.

 

[LTC8K6]

Took the battery in to get tested and the battery failed. So it was the battery that was the issue. It's not the original battery either - I bought the car used and it already had a 3rd party battery in it. Thanks all! Glad it wasn't the alternator.

Yeah, I think you needed a battery load tester to spot that one. Often the voltmeter can spot the problem, but in your case, nothing really stood out with the voltages.

Many times, the battery loses a cell, and it drops to 10 volts, which you can easily see with the voltmeter.

A load tester would have been the next step.

Or, you could have gotten a friend to check the battery voltage during cranking, and that would have showed a bad battery.

Glad you got it fixed.

 

[sontakke]

Was battery around 3 years or so? If so, as stated before, do not even bother going any further before replacing it. In the overall scheme of the things, battery is one of the cheapest consumable maintenance item when you measure it against the the miles or years. I mean if you can not afford to replace $100 battery every 3 or 4 years without even blinking an eye, you have no business of owning a car. Deposit $2 every month in the battery replacement fund if you find yourself short of $100 when the time comes to replace battery.

Yes, it is one of my pet peeve