From: JMc on
My 1997 4Runner with 203,000 miles has begun exhibiting a strange problem
that seems to be electrical. While driving the engine stumbles, the brake
light on the dash comes on, then in most cases the engine catches again, the
brake light goes out and I drive on. So far it has never actually stalled
the engine entirely, but I've lost power to a dangerous extent. Often this
happens two, three, as many as six times in succession before it seems to
clear. I've noticed a high-pitched small motor bearing noise from under the
hood at about the same time, as though a bearing in perhaps an alternator or
other similar sized unit is wearing out. Ok, I understand it is an old
enough truck that any of these things could be normal wear and tear, but it
is Christmas, and a long weekend till I might get a chance to have diag
codes read. I'm not even sure anything will have registered. I am most
puzzled by the clear connection between the brake light and the apparent
electrical problem.

Any ideas I might look at tomorrow, any hope that the brake light indicator
is just an indicator that some code is being logged?

Thanks,
Jere

From: Anyolmouse on

"JMc" <mcdonaldjc(a)verizon.net> wrote in message
news:hh3m07$7cl$1(a)news.eternal-september.org...
> My 1997 4Runner with 203,000 miles has begun exhibiting a strange
problem
> that seems to be electrical. While driving the engine stumbles, the
brake
> light on the dash comes on, then in most cases the engine catches
again, the
> brake light goes out and I drive on. So far it has never actually
stalled
> the engine entirely, but I've lost power to a dangerous extent. Often
this
> happens two, three, as many as six times in succession before it seems
to
> clear. I've noticed a high-pitched small motor bearing noise from
under the
> hood at about the same time, as though a bearing in perhaps an
alternator or
> other similar sized unit is wearing out. Ok, I understand it is an
old
> enough truck that any of these things could be normal wear and tear,
but it
> is Christmas, and a long weekend till I might get a chance to have
diag
> codes read. I'm not even sure anything will have registered. I am
most
> puzzled by the clear connection between the brake light and the
apparent
> electrical problem.
>
> Any ideas I might look at tomorrow, any hope that the brake light
indicator
> is just an indicator that some code is being logged?
>
> Thanks,
> Jere
>

When I had an alternator problem in my '87 PU the brake light and
alternator (charge) light both came on. Does the charge light come on
when you turn the key prior to starting the engine? Maybe the bulb is
burned out?

How long has it been since the alternator was replaced? 203,000 miles is
a long time for the original to last.

FWIW, I had the alternator freeze up in a Chevy Lumina while doing 6o
mph. It stopped the engine completely and I slid off of the highway. I
was just outside of a small town and had some of my tools with me. So I
took off the serpentine belt and drove it to the only garage for miles
around.

--
We have met the enemy and he is us-- Pogo

Anyolmouse


From: JMc on
Thanks for suggestions:
The alternator is original, (as is everything else but fluids, tires, brake
pads and the throttle positioning sensor). Charge indicator does illuminate
when I turn key on before starting, but has not yet ever lit during one of
my episodes. I'll stay off highways and below 60 till I sort this out.
Fortunately, it is manual trans and I can control potential skidding with
application of clutch. I'll give an update after some more thought and
investigation tomorrow.

Thanks again

"Anyolmouse" <Anyolmouse(a)invalid.invalid> wrote in message
news:Y5fZm.10091$Gf3.313(a)newsfe18.iad...
>
> "JMc" <mcdonaldjc(a)verizon.net> wrote in message
> news:hh3m07$7cl$1(a)news.eternal-september.org...
>> My 1997 4Runner with 203,000 miles has begun exhibiting a strange
> problem
>> that seems to be electrical. While driving the engine stumbles, the
> brake
>> light on the dash comes on, then in most cases the engine catches
> again, the
>> brake light goes out and I drive on. So far it has never actually
> stalled
>> the engine entirely, but I've lost power to a dangerous extent. Often
> this
>> happens two, three, as many as six times in succession before it seems
> to
>> clear. I've noticed a high-pitched small motor bearing noise from
> under the
>> hood at about the same time, as though a bearing in perhaps an
> alternator or
>> other similar sized unit is wearing out. Ok, I understand it is an
> old
>> enough truck that any of these things could be normal wear and tear,
> but it
>> is Christmas, and a long weekend till I might get a chance to have
> diag
>> codes read. I'm not even sure anything will have registered. I am
> most
>> puzzled by the clear connection between the brake light and the
> apparent
>> electrical problem.
>>
>> Any ideas I might look at tomorrow, any hope that the brake light
> indicator
>> is just an indicator that some code is being logged?
>>
>> Thanks,
>> Jere
>>
>
> When I had an alternator problem in my '87 PU the brake light and
> alternator (charge) light both came on. Does the charge light come on
> when you turn the key prior to starting the engine? Maybe the bulb is
> burned out?
>
> How long has it been since the alternator was replaced? 203,000 miles is
> a long time for the original to last.
>
> FWIW, I had the alternator freeze up in a Chevy Lumina while doing 6o
> mph. It stopped the engine completely and I slid off of the highway. I
> was just outside of a small town and had some of my tools with me. So I
> took off the serpentine belt and drove it to the only garage for miles
> around.
>
> --
> We have met the enemy and he is us-- Pogo
>
> Anyolmouse
>
>
From: Jeff on
Do you have the optional 4 wheel brake equalizer gadgetry, AntiLock, or
whatever they call it? "Brake Light" makes ME think BRAKES! I never
liked the looks of all that plumbing...

Or... the optional automatic locking, i.e., vacuum operated, front
differential comes to mind. Another plumber's bad dream.

Check your wiring, including grounds?

Yea, I dread those unpredictable power-drops in the middle of nowhere!

Take care, and Good Luck!
From: JMc on
I do ABS brakes, though they are factory. But you raise a good point. I am
now thinking the Brake light on the dash is a result rather than a source
indicator. My sense is the electrical interruption is long enough for the
ABS circuitry to sense and it is lighting the dash light to indicate they
are not ready for emergency stopping.

I am back to tracing the electrical feeds from battery, alternator, starter
and ground. It's pouring rain, melting our snow pack, and even a dry garage
is not a comfortable place for crawling around, but better than a ditch
somewhere.

Thanks,
Jere

"Jeff" <Not(a)dot.net> wrote in message
news:4b35a9ea$0$30841$822641b3(a)news.adtechcomputers.com...
> Do you have the optional 4 wheel brake equalizer gadgetry, AntiLock, or
> whatever they call it? "Brake Light" makes ME think BRAKES! I never liked
> the looks of all that plumbing...
>
> Or... the optional automatic locking, i.e., vacuum operated, front
> differential comes to mind. Another plumber's bad dream.
>
> Check your wiring, including grounds?
>
> Yea, I dread those unpredictable power-drops in the middle of nowhere!
>
> Take care, and Good Luck!