two ECT sensors?

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Old 29 Sep 2008, 05:35 pm   #1 (permalink)
mrdarrett@gmail.com
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Default two ECT sensors?

My '96 camry (I4, auto trans) seems to have TWO engine coolant temp
sensors just to the left of the upper coolant hose. The one on the
right is the one connected to the engine temp gauge in the dashboard
(confirmed that by unplugging it, checking, and replugging), but what
does the temp sensor on the left do?

Do they both connect to the ECM, ???

Thanks,

Michael
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Old 29 Sep 2008, 11:29 pm   #2 (permalink)
johngdole@hotmail.com
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Default Re: two ECT sensors?

The varister allows the ECM to calculate all sorts of stuff. It's for
engine control only. You can calculate things such as if the engine is
cold (ECT and intake air temp (IAT) about the same) or at operating
temperature. So EGR kicks in, transmission shifts into OD, etc.

The other is just for the gauge.

On Sep 29, 3:35*pm, mrdarr...@gmail.com wrote:
> My '96 camry (I4, auto trans) seems to have TWO engine coolant temp
> sensors just to the left of the upper coolant hose. *The one on the
> right is the one connected to the engine temp gauge in the dashboard
> (confirmed that by unplugging it, checking, and replugging), but what
> does the temp sensor on the left do?
>
> Do they both connect to the ECM, ???
>
> Thanks,
>
> Michael


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Old 30 Sep 2008, 12:42 pm   #3 (permalink)
Daniel
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Default Re: two ECT sensors?

One sensor goes to the gauge, the other to the computer.
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Old 30 Sep 2008, 01:26 pm   #4 (permalink)
mrdarrett@gmail.com
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Default Re: two ECT sensors?

On Sep 30, 10:42*am, Daniel <nospampls2...@yahoo.com> wrote:
> One sensor goes to the gauge, the other to the computer.



Exact same gauge though right? same model #, etc???
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Old 30 Sep 2008, 05:35 pm   #5 (permalink)
mrdarrett@gmail.com
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Default Re: two ECT sensors?

On Sep 29, 9:29 pm, johngd...@hotmail.com wrote:
> The varister allows the ECM to calculate all sorts of stuff. It's for
> engine control only. You can calculate things such as if the engine is
> cold (ECT and intake air temp (IAT) about the same) or at operating
> temperature. So EGR kicks in, transmission shifts into OD, etc.
>
> The other is just for the gauge.



That's incredibly wasteful.

Only need one gauge to send a signal to the computer. For pennies in
transistors and capacitors, the ECM can then send an analog
temperature signal to the gauge.

The ECT sensor is at least $15 (aftermarket), more for Toyota parts.

Hmm... more $$$ for Toyota...

Michael
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Old 30 Sep 2008, 07:59 pm   #6 (permalink)
johngdole@hotmail.com
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Default Re: two ECT sensors?

No, I don't think so. The gauge temperature "sender" is a cheap one
wire deal. The ECM coolant temperature "sensor" is a variable thermo-
resistor, two wires, double the price of the gauge's temperature
sender.



On Sep 30, 11:26*am, mrdarr...@gmail.com wrote:
> Exact same gauge though right? *same model #, etc???


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Old 30 Sep 2008, 08:10 pm   #7 (permalink)
johngdole@hotmail.com
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Default Re: two ECT sensors?

I think you are absolutely right. In fully computerized cars there is
no reason why the ECU couldn't send the SAME SIGNAL to a gauge, or to
control the EGR valve with a stepper motor

But you'll find things like that only in the world's most advanced
Bosch Motronic engine control systems, not in cheaper cars. In fact,
in some later Motronic versions there are no oil dipsticks, even oil
level is measured electronically! I suppose that's necessary for dry
sump systems?



On Sep 30, 3:35*pm, mrdarr...@gmail.com wrote:
> That's incredibly wasteful.
>
> Only need one gauge to send a signal to the computer. *For pennies in
> transistors and capacitors, the ECM can then send an analog
> temperature signal to the gauge.
>
> The ECT sensor is at least $15 (aftermarket), more for Toyota parts.
>
> Hmm... more $$$ for Toyota...
>
> Michael


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Old 30 Sep 2008, 11:42 pm   #8 (permalink)
mrdarrett@gmail.com
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Default Re: two ECT sensors?

Yeah, I noticed that. One wire on the gauge, two wire for the ECM
sensor.

At first I was tempted to splice and solder, then thought, naah, what
am I thinking... went to napaonline.com, kragen.com, autozone.com, and
got one from Napa for $21.

I hope this solves my warm stalling problem. My problem is remarkably
similar to this one:
http://toyotaownersclub.com/forums/i...5&#entry618097

I had replaced a coolant sensor, but it turns out that was the gauge
sensor, not the ECT/ECM sensor... d'OH!

So far so good... went on a long-ish trip (only stalls after about 10
miles, when warm, and then only once a month or so), no problem so
far...

Thanks,

Michael



On Sep 30, 5:59 pm, johngd...@hotmail.com wrote:
> No, I don't think so. The gauge temperature "sender" is a cheap one
> wire deal. The ECM coolant temperature "sensor" is a variable thermo-
> resistor, two wires, double the price of the gauge's temperature
> sender.
>
> On Sep 30, 11:26 am, mrdarr...@gmail.com wrote:
>
> > Exact same gauge though right? same model #, etc???


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Old 01 Oct 2008, 10:53 am   #9 (permalink)
mrdarrett@gmail.com
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Default Re: two ECT sensors?

On Sep 30, 5:59 pm, johngd...@hotmail.com wrote:
> No, I don't think so. The gauge temperature "sender" is a cheap one
> wire deal. The ECM coolant temperature "sensor" is a variable thermo-
> resistor, two wires, double the price of the gauge's temperature
> sender.
>
> On Sep 30, 11:26 am, mrdarr...@gmail.com wrote:
>
> > Exact same gauge though right? same model #, etc???



I noticed that the car runs a lot smoother with the new ECT sensor.
Maybe it's my imagination...? ;-) Even the transmission shifts seem
smoother... before, when I reached 40 mph and released the gas, the
transmission would make a thud and the car would shudder a bit. Not
so much now... a little bit, but only because I'm listening for it...
(should I go for synthetic Dexron 3?)

Michael
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Old 01 Oct 2008, 11:00 pm   #10 (permalink)
johngdole@hotmail.com
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Default Re: two ECT sensors?

In worst case the ECM may not have entered into closed loop control.
It's the only way the ECM knows about operating temperature.

As far as GM is concerned, they no longer license the Dexron II/III
name. Today's official "Synthetic Dextron III" is actually "Dexron
VI", as the following article pointed out. But I've never found a need
other than generic "Dexron III-compatible" from Walmart, plus dropping
the pan and changing out the strainer periodically.

"Dexron-VI licensed fluids are fully backward compatible and may be
used in all applications covered by earlier GM ATF specifications, it
advises."

http://www.imakenews.com/lng/e_artic....cfm?x=b11,0,w



On Oct 1, 8:53*am, mrdarr...@gmail.com wrote:
> I noticed that the car runs a lot smoother with the new ECT sensor.
> Maybe it's my imagination...? *;-) *Even the transmission shifts seem
> smoother... before, when I reached 40 mph and released the gas, the
> transmission would make a thud and the car would shudder a bit. *Not
> so much now... a little bit, but only because I'm listening for it...
> (should I go for synthetic Dexron 3?)
>
> Michael


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