Automatic transmission queries

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Mar 3, 2006
King Island Tasmania Australia
I have an '05 100 series TD LC (8K kms on the clock) with an Automatic transmission. I have noticed recently on going down a long descent above 75km/hr if I touch the brakes the transmission will change down to 4th and atleast once down to 3rd. I am sure that this has not always been the case. Is this normal. To get it back into 5th I need to accelerate and then deccelerate. I am also unsure if the automatic change criteria is constant. Sometimes I think that it changes up too easilywhen I accelerate. Also does any body know exactly what happens to the gear change criteria when the ECT is selected. I can't seem to figure what actually changes.
My 5 speed Allison tranny in my Chevy Diesel does this by design.

The new 5 speed Toyota with the Diesel may do it as well. It is helping the engine brake you down long grades.

Is there a performance or tow/haul button on the vehicle?
Thanks. It did make sense but I have never noticed it before. The Owners Manual does not mention it, but then again the OM is a bit of a dog!
G'day to King Island in the Strait
AI (Artificial Intelligence)- SHIFT Control
1) General
In addition to the switching of the shift pattern through the pattern select switch, the AI- SHIFT control enables the ECM to estimate the road conditions and the driver’s intention in order to automatically switch the optimal shift pattern. As a result, comfortable ride has been realized at high levels.
2) Road Condition Support Control
Under road condition support control, the ECM determines throttle valve opening angle and the vehicle speed whether the vehicle is being driven uphill or downhill.
To achieve an optimal drive force while driving uphill, this control prevents the transmission from upshifting to the 4th or 5th gear. To achieve an optimal engine brake effect while driving downhill, this control automatically downshifts the transmission to the 4th or 3rd gear.
3) Driver’s Intention Support Control
Estimates the driver’s intention based on the accelerator operation and vehicle condition to switch to a shift pattern that is well-suited to each driver, without the need to operate the shift pattern select switch.
This is for 2003 5 speed auto, the later 5 speed may have slightly different shift points and AI.
By the way, I have had my tranny ECU replaced due to the fact it would change back to 3rd going downhill, then would not change back up until you shut the engine off on the side of the road!
This pic may give you an idea
Thanks for the detail. However where does the "ECT" fit into the above. Is your diagram "with control" what happens with the "ECT". This up changing happens with or without the "ECT" switched on. I assume the "2nd start" is just a matter of dropping off 1st gear. Does it impact on the other change criteria. My preference (driving style) is to try and allow the vehicle to stay in 5th as long as possible for economy and reduced engine noise levels.
ECT POWER is the mode with the button pushed in, it makes the kickdown happen earlier, just the same as ECON mode on australian cars, if you don't have econ switched on then you kickdown earlier. So leave the ECT power button off to save fuel and change into 5th earlier.
Sorry forgot to answer the other part of the question, the without control, is what it was like without Artifical intelligence, and with control is with it. You can't turn it off. It is inbuilt into the 03 onwards 5 speed tranny ECU. ECT power would probably change earlier again going up the hill.

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