: Reset Transmission???

07-21-07, 08:16 PM
Does anyone know if it is possible to reset or erase the memory in the transmission of a V8 awd STS? My car, '05 STS4 V8, has gone back to horrible shifting that was finally cured by a TSB. That lasted about 8k miles. Now it is back to up shifting horribly, near impossible downshifts with hesitation and confusion, and general clunks and clanks at all speeds regarding gear change. Since it seems to relearn this improper behavior I was thinking a relearn might prevent another argument with the dealer. I tried disconnecting it for the night but the memory of everything remained including radio, etc.

07-25-07, 12:28 AM
Why not get the dealer to reflash the memory. You may have had some transient voltage surge that un-did what the TSB corrected. I got the software upgrade months ago (see my response under this subject thread elsewhere in this blog) and it still works just fine. If anything, my transmission stays in gear longer than I would ideally want and I find myself manually shifting into M5 and back to sD just to ease the wallet burn.

07-26-07, 07:46 PM
yeah, i don't think these transmissions learn anything from your driving style anyway.

07-27-07, 08:16 PM
There is a manual reset procedure that you do with the Tech 2 to "reset the TAPS".
Basically the transmission monitors input and output shaft speed and times each shifting event. The theory is that it can control shift feel if it keeps the shift inside a certain window of operation.
It adjusts line pressure and solenoid activation accordingly. It does learn patterns in your driving.
If your wife is the primary driver her "style" may be different than yours and it may be anticipating her actions but getting yours.

You should be able to reset the adapts by disconnecting the battery and connecting the positive and negative cables together AFTER the battery is unhooked of course.
This may not work, but it is really the only thing you can do without a scan tool. The software we use to "reprogram" your ECM gives us a warning message if we try to use the same calibrations, but it does wipe out all the stored shift adapts and fuel trim table data.
That is probably what happened before.
If you know someone with a Tech 2 they could do it, or if you just take it to the dealer and ask them to reset the shift adapts or clear the TAPS they should be able to do it for you... even though they may want to charge you.


07-28-07, 08:37 PM
Thank you. Touched the pos and neg cables together after disconnect. Will let you know. Thank you again.

07-30-07, 08:11 PM
Well despite touching the pos and neg batt cables together the problem persists. The car still downshifts when coming to a stop so hard that it lurches and people's head bump the headrests! When letting off the gas to coast the car lurches on and off. Overall all the shifts are hard and sloppy until the rpms exceed approx 4k. I will take it back to the dealer and start the arguing all over again.

07-31-07, 05:14 PM
Take them for a ride, show the shop foreman or a transmission tech what you are talking about.
Maybe something is actually not right with the trans?

08-02-07, 02:01 PM
It does learn patterns in your driving.
If your wife is the primary driver her "style" may be different than yours and it may be anticipating her actions but getting yours.

Does it lump driver 1 & 2 together or separate the driving styles of 1 & 2 and then perform differently for each driver accordingly? (that might be wishful thinking)

08-02-07, 06:25 PM
I don't believe they do that.
The ECM and TCM memory is not split up like that.
It just has one set of adapts for transmission control and engine control (for fuel).

It would be nice if they set it up that way, but alas they do not.
Interesting question though.

05-27-11, 07:42 AM
Did you find a long term solution to this problem?My 07 SRX does exactly the same thing - after a few thousand KM the transmission will not shift unless I press the throttle about half way to the floor - the car barely accelerates (again unless the pedal is floored) and fuel milage around town is terrible. The dealer reflashes the tranmission ECU (or something like that) and the car drives perfectly for a while before the fault returns.
Have lived with this for a year - the dealer cannot fix and I cant tolerate any longer. Need to fix or the car needs to go!

05-27-11, 10:38 AM
Holy thread resurrection! :D I would think that if the dealer you are taking the car to can't fix it, then a different dealer is needed.

06-18-11, 09:59 AM
The dealer is in the UAE - and I dont think many people drive on a little throttle here ....

But I am beginning to suspect I have two simultaneous problems - the shifting issue below plus the infamous 'chuggle'. They may have fixed the shifting problem but the chuggle (or torque converter replacement) looks like a battle I cant win as they just dont recognise the problem.

so desperately looking for advice on how to persuade the dealer there is a problem to fix ...


06-18-11, 12:46 PM
How about cleaning the injectors and throttle body? what could be desirable shift point based upon fuel input, solenoid pressure, and other computer stuff being discussed beyond my pay grade, that is it doesn't take into account the accumulating carbon, less power and vaccum pressures at the same previous rpms that would create a smooth shift? totally guessing, awd always scares me....

Is their a similar issue on rwd? mine runs generally smooth but recently sometimes overdrive lockout (4) or a manual (+, -) approach keeps the engine from settling into very low 5th gear rpm pulls at 35-45 low uphill grades - i think i read this as chuggle before.

06-19-11, 02:12 PM
The throttle-closed position is re-calibrated at every start. Carbon buildup can lead to a lot of odd issues.

06-19-11, 10:39 PM
reading and writing tired = their and there confusion

06-20-11, 02:01 PM
I have an '05 STS V8 and I'm experiencing similar problems with harsh shifting 99% of the time, especially from 1st to 2nd. Very rarely shifting will smooth out somewhat for a few miles, but then will return. It's so bad that I have to let up off the gas to allow the transmission to shift or else the shift will be so harsh that the front end will lift up and the rear tire will chirp. When making a turn the harsh shifting can cause one rear will to lose traction causing the car to slide sideways a bit. It looks like I need to take my STS to a dealership for a software upgrade.