Question About Normal Auto Trans Behavior

Hi All,

So I took a trip with the wife and kids from Kentucky to Virginia and back (in-laws) this past week and a most likely novice question popped into my head about how the gearing in the 2nd Gen Tacoma A/T works.

So I'm driving along in level terrain at about 75 with cruise control on turning about 2300 RPM. As I would start climbing a gradual hill, there would be a sudden RPM increase to about 2600 or so. Then as the hill leveled out, it would drop back to 2300. On steeper hills, this increase from 2300 to 2600 would be followed by a larger increase to about 3300. I'm assuming the 3300 at that speed is 4th gear since when I manually shifted to 4th on level ground, the RPM would be at about 3300 as well.

So, if this is a 5 speed auto trans, what is the "in-between" gear that lives between cruising (5th) gear and 4th??

 

Your going into torque converter lock and unlock

 

overdrive

 

This

 

Now from my understanding, torque converter lock is essentially the overdrive, correct?

 

There's no inbetween gear in our autos. You're feeling a 4th or 3rd downshift. And depending on when exactly you're feeling it, you could be feeling the TCC engage (it's more than likely pulse width modulated on our transmissions, so this is unlikely). And they design them so you can't feel them engage ever.

 

No, 5th gear is overdrive


Nowadays the TCC can apply in any gear. As early as 1st and second.

 

Ahhhhh no.
The OD is a gear. The loss of 300 rpm is the t/c locking up to stop the slip inherent in it making it like a std. on the road. They change the programming from year to year and in some cases the t/c will lock and unlock in lower gears.

Ahhhhhh
Thanks Jamie...

 

I love my 6 speed.

 

That's swell

and relevant

 

Just wondering if you can see the converter locking with a scan guage or the ultraguage ?

or with the cheap tech stream cable and a lap top
Do any of these show you what gear you are in and what the trans is doing ?

 

Yes^

You'll be able to monitor TCC pulse width. Given in a voltage or percentage.

After learning in depth about autos, it was just one more reason I went for a manual.

 

Thanks Spoon !!!!

 

Listen to, Tacoma Mike, he has it correct.

 

13 replies and I barely had a chance to take a shi......

Awesome. I actually kind of wondered at the time if it was the torque converter locking/unlocking. I guess my hunch was correct. And trust me, I had plenty of time to crawl into my own head to escape the insanity that is a 3 y.o. and a 4 month old (and a wife!) on a 8.5-hour-each-way road trip.

So, when the RPM increased, I'm assuming that is the TC unlocking and the difference in RPM is basically the "slip" occurring when unlocked, correct?

Thanks Tacoma Mike, et. al!

 

That's correct

 

This.