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Replaced ECM, now trans downshifts different

 
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Old 23 Oct 2017, 05:26 pm
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Default Replaced ECM, now trans downshifts different

I just replaced the PCM/ECM for throwing a lot of codes and the CEL on. The new one eliminated that problem, but the first time driving it, I noticed it downshifting
at about 25mph under braking. It never did that before. It's not hard enough to chirp the tires, but it even does it under pretty hard braking, which surprised me. This is the only difference, it upshifts normally and the kick down is fine.
Not likely at mount thing, happened too suddenly.
Possibly the TCM not communicating with the new ECM unit?
Is there a way to reset the TCM?
This is a 2003 GT (turbo) AT.
Thanks
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Old 23 Oct 2017, 06:31 pm
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Default Re: Replaced ECM, now trans downshifts different

Quote:
Originally Posted by Jeffz View Post
I just replaced the PCM/ECM for throwing a lot of codes and the CEL on. The new one eliminated that problem, but the first time driving it, I noticed it downshifting
at about 25mph under braking. It never did that before. It's not hard enough to chirp the tires, but it even does it under pretty hard braking, which surprised me. This is the only difference, it upshifts normally and the kick down is fine.
Not likely at mount thing, happened too suddenly.
Possibly the TCM not communicating with the new ECM unit?
Is there a way to reset the TCM?
This is a 2003 GT (turbo) AT.
Thanks
Did you try applying the manual Quick Learn procedure? There is also an electronic Quick Learn procedure, but must be done at a dealership or transmission shop that has the proper equipment.
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Old 23 Oct 2017, 08:14 pm
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Default Re: Replaced ECM, now trans downshifts different

"QUICK LEARN PROCEDURE
The quick learn procedure requires the use of the scan tool. This program allows the PCM to recalibrate itself. This will provide the best possible transaxle operation.
NOTE: The quick learn procedure should be performed if any of the following procedures are performed:
* Transaxle Assembly Replacement
* Powertrain Control Module Replacement
* Solenoid/Pressure Switch Assembly Replacement
* Clutch Plate and/or Seal Replacement
* Valve Body Replacement or Recondition
To perform the Quick Learn Procedure, the following conditions must be met:
* The brakes must be applied
* The engine speed must be above 500 rpm
* The throttle angle (TPS) must be less than 3 degrees
* The shift lever position must stay until prompted to shift to overdrive
* The shift lever position must stay in overdrive after the Shift to Overdrive prompt until the scan tool indicates the procedure is complete
* The calculated oil temperature must be above 60 and below 200
1. Plug the scan tool into the diagnostic connector. The connector is located under the instrument panel.
2. Go to the Transmission screen.
3. Go to the Miscellaneous screen.
4. Select Quick Learn Procedure. Follow the instructions of the scan tool to perform the Quick Learn Procedure."


By the way this Quick Learn Procedure is for a 2006 PT Cruiser.

The Quick Learn Procedure might not be necessary if the latest firmware has been already completed. Some members have posted wasting their money having the firmware updated only to find out the problem was elsewhere in the transmission.

I would recommend checking to see if you have any transmission diagnosis codes being triggered.
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Last edited by ptcruisersteve; 23 Oct 2017 at 09:26 pm.
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Old 23 Oct 2017, 09:28 pm
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Default Re: Replaced ECM, now trans downshifts different

Quote:
Originally Posted by ptcruisersteve View Post
"QUICK LEARN PROCEDURE
The quick learn procedure requires the use of the scan tool. This program allows the PCM to recalibrate itself. This will provide the best possible transaxle operation.
NOTE: The quick learn procedure should be performed if any of the following procedures are performed:
* Transaxle Assembly Replacement
* Powertrain Control Module Replacement
* Solenoid/Pressure Switch Assembly Replacement
* Clutch Plate and/or Seal Replacement
* Valve Body Replacement or Recondition
To perform the Quick Learn Procedure, the following conditions must be met:
* The brakes must be applied
* The engine speed must be above 500 rpm
* The throttle angle (TPS) must be less than 3 degrees
* The shift lever position must stay until prompted to shift to overdrive
* The shift lever position must stay in overdrive after the Shift to Overdrive prompt until the scan tool indicates the procedure is complete
* The calculated oil temperature must be above 60 and below 200
1. Plug the scan tool into the diagnostic connector. The connector is located under the instrument panel.
2. Go to the Transmission screen.
3. Go to the Miscellaneous screen.
4. Select Quick Learn Procedure. Follow the instructions of the scan tool to perform the Quick Learn Procedure."


By the way this Quick Learn Procedure is for a 2006 PT Cruiser.

The Quick Learn Procedure might not be necessary if the latest firmware has been already completed. Some members have posted wasting their money having the firmware updated only to find out the problem was elsewhere in the transmission.

I would recommend checking to see if you have any transmission diagnosis codes being triggered.
There is also a Quick Learn procedure in the Gen1 Service Manual.
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Old 23 Oct 2017, 09:34 pm
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Default Re: Replaced ECM, now trans downshifts different

Quote:
Originally Posted by rckstein View Post
There is also a Quick Learn procedure in the Gen1 Service Manual.
That is good to know if it is needed but I think we need to look at every possible cause first.
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Old 23 Oct 2017, 10:54 pm
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Default Re: Replaced ECM, now trans downshifts different

Quote:
Originally Posted by ptcruisersteve View Post
That is good to know if it is needed but I think we need to look at every possible cause first.
This is what is stated in the Gen1 Service Manual about the Quick Learn:



IMO, the OP should look at things related to replacement of the PCM/ECM first and finish that project, before moving on to looking at other possible causes, when the present issues may be directly related to the replacement of the PCM/ECM.

Recently, Todd posted a link to download the manual Quick Learn procedure, but I can't find that link now.

But what has not been answered, by anyone of authority or expertise, is: Will the manual Quick Learn procedure do just as much as the dealer downloaded electronic version? Or does the dealer electronic download version get deeper into the bowels of the PCM/ECM to reset those items that only the electronic version can do?

But the OP could also try this reset procedure, that was sent to my by the seller that I got my replacement PCM from when, after replacement, my PT experienced some minor shifting issues:

* remove negative battery terminal
* remove positive battery terminal
* touch the negative and positive battery terminals together for at least 45 seconds, leave them disconnected from the battery
* disconnect all the connectors from the PCM and leave them disconnected for at least 1 hour
* after at least 1 hour has expired, reconnect the PCM connectors
* reconnect the positive battery terminal
* reconnect the negative battery terminal

Start vehicle and drive as normal.

It's not going to hurt anything to try the above reset procedure.
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Old 24 Oct 2017, 12:21 am
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Default Re: Replaced ECM, now trans downshifts different

Thanks guys.
Rckstein, thanks for passing on your vendor's suggested procedure. Did it help, in your case?
I agree with a suggestion that the trans fluid and filter should be changed every year/15k miles. It doesn't cost much if you DIY, and can prevent very expensive repairs.
Since my local AAMCO is much closer than the Dealer, I will have them change fluid&filter and hopefully solve any electronic issues.
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Old 24 Oct 2017, 12:51 am
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Default Re: Replaced ECM, now trans downshifts different

Quote:
Originally Posted by Jeffz View Post
Thanks guys.
Rckstein, thanks for passing on your vendor's suggested procedure. Did it help, in your case?
I agree with a suggestion that the trans fluid and filter should be changed every year/15k miles. It doesn't cost much if you DIY, and can prevent very expensive repairs.
Since my local AAMCO is much closer than the Dealer, I will have them change fluid&filter and hopefully solve any electronic issues.
It seemed to initially, but then I didn't drive it very much before there was a complete failure of the transmission solenoid pack, which may have been the problems and not the new PCM. I had the transmission solenoid pack replaced at a shop, and I don't think that they programmed electronically the Quick Learn procedure, as detailed per the Service Manual. That shop finally sent me to a specialty transmission shop and they programmed in the Quick Learn procedure. All has been fine since the reprogramming.
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Old 24 Oct 2017, 01:05 am
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Default Re: Replaced ECM, now trans downshifts different

Maybe I should put 100 or so miles on it, and see if it cures itself. If so, I can DIY the fluid change. If not, I'll try the vendor's procedure, then AAMCO or Dealer service.
Thanks again!
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Old 24 Oct 2017, 01:32 am
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Default Re: Replaced ECM, now trans downshifts different

Quote:
Originally Posted by Jeffz View Post
Thanks guys.
Rckstein, thanks for passing on your vendor's suggested procedure. Did it help, in your case?
I agree with a suggestion that the trans fluid and filter should be changed every year/15k miles. It doesn't cost much if you DIY, and can prevent very expensive repairs.
Since my local AAMCO is much closer than the Dealer, I will have them change fluid&filter and hopefully solve any electronic issues.
Let us know what codes you find at AAMCO.
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