Yesterday my '97 4Runner (V6) slowly lost power, as if the alternator died and thus was being run by battery only. Ordinarily, wouldn't the battery light illuminate if the alt was failing to charge? (scratching head).

Instead, the first indicator was the ABS light, then the RPM meter zeroed, radio cut out, lights out, then couldn't shift out of PARK, then engine died. I then replaced both shoddy battery cable terminals, same problem. A multi-meter confirmed that--after jumpstarting-- the battery was being drained while running until it quit.

I'll continue to troubleshoot alternator issues, but I'm stymied as to why the truck doesn't pick up any alt problems when it should. Or could there be any other usual suspects? Battery is 2 years old, btw, and the symptoms were sudden. Thanks!

I KNOW THE FIX , I literally just had this prob last week!!! (monday this week)

First check your posts but for sure SWAP YOUR ALT!!! It is the voltage regulator which is 130 new, so not worth it, get a new alt. an your trobles will be fixed.


Hope this help but it's for sure your alt

Do the "post test" or what ever it's called, while car is on remove the pos post from bat and if she cuts off its your alt

NEVER REMOVE THE BATTERY CABLES WHILE THE CAR IS RUNNING! It could cause a surge that could blow out lots of electrical components. That might have worked in the 40's or maybe it's an old wives tale but you don't want to ever do it to find out.
I don't know why the light didn't come on, could be due to a bad battery while the alternator is still trying to charge it but check the charging voltage on the battery with a DVM and if it's not around 13.6-14.5 volts with the engine running then the alternator is bad or the battery has a shorted cell. Have the battery checked with a load tester and if it passes then the problem is the alternator. The engine shouldn't die if the alternator quits, it should run for a few hours on just the battery if the battery is good. Once I drove from L.A. to New Mexico on just the battery!
BTW, batteries only last about 2 years here then suddenly die because of the heat.

Thanks gang. Steve, impressive on the trip from LA to NM on just the battery...was the car attached to it? lol. j/k

While troubleshooting, I jumpstarted her, ran for a few minutes, disconnected the jumper cables, then witnessed as the rig slowly lost power via multimeter. If I cut 'er off before losing too much juice, I can still easily restart. Sooo, my thought is that if the battery was suddenly bad, she wouldn't start, or would have trouble starting, but those weren't my symptoms.
Yes, disconnecting the + terminal does kill the engine abruptly.

All symptoms indeed point to the alternator, thanks 3rd Gen King. But....why didn't the batt light illuminate? Not even a check-engine light came on while she was dying. Not that I'd expect a C.E. light, but I WOULD expect the batt light to come on. (It makes me think that the alt is indeed whipping out voltage, but it's somehow not getting to the battery. That'll be my next inquiry this weekend)
I've redone this drill several times with the same results. BTW, upon starting the engine, all lamps turn on for a second, including the batt lamp, so I know the bulb's not blown.

SO NOW, if it is indeed the alt, any pros or cons with the regular go-to's? AutoZone, Advance, Napa, etc...? Years ago I heard rumors on poor quality electrical components from some of these places.

being that the abs is highly important Im under the assumption all components related to it are metered very well so your not SOL with no abs or braking system.

Mine was exactly the same but my airbag and abs (both sensitive) came on then my batt light would flicker.

As for the alt, not many shops rebuild them any more but if you have a Toyota alt it would be good to rebuild it. You can also have them pump up the amps if you want. But hey, I've gotten an autozone alt and it lasted.

So, I thought that I'd throw out a crazy thought. Is the alt bulb burnt out?

You mean the batt light?
If so

He said when he starts her up all the lights come on like normaL

Damn; I need new glasses.

Ok, thanks for the info. On other cars in the past, I've been happy with AutoZone's alternators, even though I'd have to replace them (for free) after every 2 years or so.... Not sure what's in there now. Any higher-amp alternator recommendations that are a direct bolt-on to the '97 V6?

I'll report my findings after tinkering/swapping out this week. Stay tuned, and thanks 3GK!
-Alan
Charlotte, NC

My 2000 sr5 did the same thing yesterday! The ABS light came on for the first time in the five years I've had the vehicle. Shortly after I lost all rpms, battery immediately died and couldn't even turn my hazards on. I checked the brake fluid, it was on the minimum line, filled up the brake fluid got a jump and had no issues on the hour ride home (this happened in the mountains). Is it possible that because the brake fluid needed fluid the car disabled itself before braking ability was lost?