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How does auto transmissions `shift ?

I am curious as to how much the Throttle Position, or the Sensing there of, has to do with how the Trans Shifts? I think I know the answer in a Shade Tree kind of way, but I wanna know the Technical Answer? :confused:

:rolleyes:
Hi J.C.
I don't know `if the below will help you or not ?
I don't know a lot, but I do keep files & I am constantly
searching for answers `bout everything.

I'm a student of Google's & all Web Search Engines.
I enjoy searching/finding & learning so many things on
the World Wide Web. :eek:
I really don't know how anyone can get bored `if they
are connected 4-Sure!

I hope that you & Member's enjoy the below & that it
will help member's with a better understanding
of the automatic transmission.
I keep learning so much here on the MCF,
some good and some bad, but it's fun
and rewarding.
EnJoy
:)
A Short Course on

Automatic Transmissions

<small style="font-size: 10px;">by Charles Ofria</small>

http://image.cpsimg.com/sites/carpar...ivetypical.gifThe modern automatic transmission is by far, the most complicated mechanical component in today's automobile. Automatic transmissions contain mechanical systems, hydraulic systems, electrical systems and computer controls, all working together in perfect harmony which goes virtually unnoticed until there is a problem. This article will help you understand the concepts behind what goes on inside these technological marvels and what goes into repairing them when they fail.

This article is broken down into five sections:

What is a transmission breaks down in the simplest terms what the purpose of a transmission is.
Transmission Components describes the general principals behind each system in simple terms to help you understand how an automatic transmission works.
Spotting problems before they get worseshows what to look for to prevent a minor problem from becoming major.
Maintenancetalks about preventative maintenance that everyone should know about.
Transmission repairsdescribes the types of repairs that are typically performed on transmissions from minor adjustments to complete overhauls.

http://www.carparts.com/transmission.htm

:rolleyes:
Click above to continue
(Source link above)

Since these transmissions are almost completely computer controlled, the TPS and MPH has a LOT to do with the trans shifting. Messing with a tuning device, I can see the various tables for the trans and there is a lot of dependency on those two values for when and how it shifts.

Thanks Space and Jason! I don't know if you can tell or not but my computer background is causing me to ask extra questions to get a better understanding not only of my problem but to gain more Car K-Nowledge in general!
So the P0121 and P0122 codes in my computer could be causing erratic behavior in my transmission?
This is what its doing;
1) Hitting a little hard on up shifts
2) Hitting very hard from 2nd to 3rd gear
3) Will not Down Shift in 3rd or 4th gear during WOT
4) Serge's in 3rd gear only, just slightly, maybe 200 or 300 rpm.
If I go WOT from a stand still, like after paying the Pkway Tolls, it seems to shift fine all the way through the gears with no surging in 3rd. Lastly, I think it is revving a little Hi in all gears. At 65 MPH its at 2300 to 2600 RPMs and Up hill in any gear it can be as Hi as 2900 RPMs on a Medium up hill grade! I'm about to go out and do the TPS circuit test I got for Jason. Had to let the Engine Cool down after my morning Wall-Mart run! :confused: Thanks Guys! You really are a Big Help!!!!! :thumbsup:

Well I untaped the wire harness to the computer. Pulled out the Dk Blue TB signal wire and found it had been butt connected twice. Once about 2" from the computer and the next one about 3" from that. The closer one was broken and chipped with exposed wire. So I cut them Both out and put a new butt connector in making sure that Both wire ends passed through the center. Then crimped the butt connector on the ends and then in the middle.
Then I took her out on a 30 mile cruise to test her out.
Smooth shifts in every gear. Down shifting in every gear. Lower RPMs when cruising. And no surging in third. I may have to take that whole harness apart and check every wire! We'll see how she runs on the 22 mile trip to work in the morning. For now, it's good ending to a stressful day!