92 FJ80 - Dead Battery Mystery

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Ok, I have a good one for you guys. So we've noticed that our '92 Cruiser's battery seems to die at near random points. It originally died after we brought it home from the PO which was a long drive in the rain. (Wipers, lights, heat all on) So we thought alternator.

We've checked and tightened the battery terminals, and I recently had the alternator checked at my local Toyota dealership. (They told me it was fine.) Ran it a few days, using the heat, lights, and radio and everything seemed fine. Then today, maybe a week since the last incident, it died again. (Today it rained so we were using the wipers again.)

I've also noticed that my wiper blades seem to move slower than any other vehicle i've driven. (Not sure if that's just an FJ80 thing?) Think the motor could be causing a short or something?

Also my radio display almost always remains blank even though I can still listen to the radio.

Not sure where to go next, we have another battery to try. Wondering what everyone can drum up?

Thanks in advance guys.
 
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Feb 10, 2013
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Check the voltage of the battery with the car off and running to determine if your battery is charged and if your alternator is charging

Then I would check the draw on the battery with car off. Should be .05 and less. Any more and you have a drain somewhere.
 
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Yup. Check for a parasitic draw. There's a couple of good youtube videos that explain how to do it. Very simple to diagnose if you buy a cheap multi-meter. HF, Sears, Home Depot - they all sell them.

Good luck!
 

jonheld

 
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How old is the battery? They have about a 5 year lifespan in the northeast.
Also, please explain what you mean by "died". Were you driving and it cut off? Did you stop and try to restart and she wouldn't crank?
 

SUMMIT CRUISERS

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if the engine is running and the wipers are slow, radio is blank/dim, I would bet the alternator is not delivering the proper charge to the battery.
 
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How old is the battery? They have about a 5 year lifespan in the northeast.
Also, please explain what you mean by "died". Were you driving and it cut off? Did you stop and try to restart and she wouldn't crank?
Died: as in operating fine, then parked for an hour. My mother goes back in the truck to take it somewhere and it doesn't start. She said it had a very slow crank but wouldn't start without a jump. I'm betting on the parasitic drain at the moment.
 

jonheld

 
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Died: as in operating fine, then parked for an hour. My mother goes back in the truck to take it somewhere and it doesn't start. She said it had a very slow crank but wouldn't start without a jump. I'm betting on the parasitic drain at the moment.
How old is the battery?
What is the voltage at the battery with the engine running?
What is the voltage at the battery with the engine off?
 
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I have no idea how old the battery is. We recently purchased off PO. Could be new or ancient.

Engine off (cold) 12.14v
Engine on (running) 13.5v
Engine off (about 5 minutes after running) 12.45v
 

jonheld

 
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12.1 is a 90% discharged battery.
Engine running should see 14.2-14.4

This is telling me that either the battery or the alternator is not doing what it's supposed to do. A battery with shorted cells can drag down alternator voltage.
A bad voltage regulator or worn out brushes in the alternator could also cause this.
My first step would be to replace the battery and start with a known good unit.
 
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Thanks for the tips, we'll throw a fresh battery in and retest. Hopefully the PO simply threw an older battery in there before selling.
 

jonheld

 
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Wouldn't a parts store be able to test the battery and alternator? Or are those tests hooey?
It depends. I had a battery tested at Sears which tested good and wouldn't hold a charge for more than a couple of days. Had it tested again and it came back bad so they replaced it. Not reliable IMO.
The OP said that Toyota tested the alternator. An alternator should be removed from the vehicle and bench tested on a proper jig to verify voltage and current output. I'd be willing to bet the dealer didn't do this.
 

LS1FJ40

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It depends. I had a battery tested at Sears which tested good and wouldn't hold a charge for more than a couple of days. Had it tested again and it came back bad so they replaced it. Not reliable IMO.
The OP said that Toyota tested the alternator. An alternator should be removed from the vehicle and bench tested on a proper jig to verify voltage and current output. I'd be willing to bet the dealer didn't do this.
I did not know this. Good info.
 
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Wouldn't a parts store be able to test the battery and alternator? Or are those tests hooey?
I've had both my local Autozone and Advance Auto do battery tests. They both say the alternator is not charging correctly. Only getting maybe 12v, and said I should be getting more like 14v.

I highly doubt the dealer did a proper test, like jonheld speculated. The dealer mechanic told me (the day I picked it up) that 13v is a common charge amount for my alternator and that it was fine. I smell BS in hindsight.

Meanwhile, simply shifting back and forth between drive, reverse (brake lights and rear lights i guess) and park is enough to put a severe strain on the battery. I regularly saw it dip well below the half mark and it failed to start back up after killing the engine.
 
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Driving around town however, I do notice the battery gauge increase with the revs. While driving the needle usually sits well above the 1/2 mark. Drops when in idle and messing with accessories.
 

jonheld

 
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I've had both my local Autozone and Advance Auto do battery tests. They both say the alternator is not charging correctly. Only getting maybe 12v, and said I should be getting more like 14v.

I highly doubt the dealer did a proper test, like jonheld speculated. The dealer mechanic told me (the day I picked it up) that 13v is a common charge amount for my alternator and that it was fine. I smell BS in hindsight.

Meanwhile, simply shifting back and forth between drive, reverse (brake lights and rear lights i guess) and park is enough to put a severe strain on the battery. I regularly saw it dip well below the half mark and it failed to start back up after killing the engine.
Keep in mind that the charging system is a "system" and not just a bunch of parts. If the battery has faulty cells it will drag down the alternator voltage putting a large load on the alternator. If your alternator is original and 25 years old, then it is well past its lifespan and a discharged battery may have ended it.
On your 92 you may have the later 90 amp alternator with internal fan that is rebuildable with OEM parts. Or you can simply get a rebuilt unit from Toyota. If you decide to replace it, then go with an OEM unit. If you go with an Autozone or other aftermarket unit, you'll get real good at replacing alternators.
 

LS1FJ40

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Keep in mind that the charging system is a "system" and not just a bunch of parts. If the battery has faulty cells it will drag down the alternator voltage putting a large load on the alternator. If your alternator is original and 25 years old, then it is well past its lifespan and a discharged battery may have ended it.
On your 92 you may have the later 90 amp alternator with internal fan that is rebuildable with OEM parts. Or you can simply get a rebuilt unit from Toyota. If you decide to replace it, then go with an OEM unit. If you go with an Autozone or other aftermarket unit, you'll get real good at replacing alternators.
Agreed. Needed an alternator on my 92 on a Saturday. Picked one up at O'Reillys. It lasted a month. Exchanged it and replaced it. It crapped out two months later. I returned it and bought an OEM one. That was 6 years ago.

I can replace an alternator in my sleep.
 
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