What controls shifting points ?

[jsoto]

SES engine light just came one. Car runs fine, has been a couple times where it felt a bit sluggish. There has been at 4X in the last 2 weeks where the it would not upshift a gear when it needed to. No transmission *errors* on the the dash.

I've yet to bring it to the shop to have the codes properly read.

[4.8isX5]

Could be cause of the code depending what it is.

Another thing to try is turn key to before-start position and hold gas all the way down for 30 sec preforms a trans reset, as it adapts to how its driven/"used to".

If code isnt part of it nor trans reset fixes, change fluid/filter/pan gasket.

[Qsilver7]

Originally Posted by 4.8isX5

...turn key to before-start position and hold gas all the way down for 30 sec preforms a trans reset, as it adapts to how its driven/"used to".

Just an FYI...that is NOT a transmission reset. This misunderstanding of how ATC (adaptive transmission control) works is incorrectly perpetuated as though the tranny is being reset...but all it does is trick the AGS (adaptive transmission systems) that makes ATC select the adaptive sport mode. After shutting down the engine or minutes of economical or granny-toe driving...the shift pattern will revert to extreme economy or economy mode.

What occurs doing the "mythic" tranny reset...vs...the data ATC is interpreting:

1. ignition on: data is ready to be collected
2. accelerator pedal is mashed to the floor (fast and held for 30 seconds): makes ATC think there's an aggressive driver
3. engine is then started without ignition being turned off: "kick fast feature" is still interpreting the fast & long press of the accelerator pedal as an aggressive driver.
4. ATC selects adaptive sport mode: transmission shifts are elongated to take better advantage of the engine's reserve power.

Doing the aformentioned "trick"...after the engine is turned off...the vehicle returns to normal XE/E/S mode based on the next driver's style of driving...the driver's influence is NEVER stored in the TCM (transmission control module)...each new driver gets a brand new adaptation...thus the car responds specifically to whomever is driving the vehicle...without a long term "learning" cycle.

Or, if the driver is not really an aggressive driver, the shift mode will return to what the driver actually is doing (normal or granny-toe mode) within minutes of being a non aggressive driver.

This is how it works, ATC will select one of 3 driving modes EVERY TIME the car is started (see driver influence & kick fast features below):

1. XE -extreme economy mode (granny-toe mode)
2. E - economy mode
3. (adaptive) sport mode

The selection is based on accelerator pedal movement (how fast & how far):

[upallnight]

Originally Posted by jsoto

SES engine light just came one. Car runs fine, has been a couple times where it felt a bit sluggish. There has been at 4X in the last 2 weeks where the it would not upshift a gear when it needed to. No transmission *errors* on the the dash.

I've yet to bring it to the shop to have the codes properly read.

Why do people come and post on here when their SES light comes on without even bothering to post the DTC? I know that they are looking for free advice, but in order to provide any advice that is meaning full they need to at the minimum post the DTC.

Do they expect that we have the gift to know what is wrong?? If I have the gift to peer into the future I would be looking at the next Powerball numbers instead of why your BM Trouble U is having problem.