Help needed reprogramming axle ratio

[rodneyiii]

Here's the deal. I have a 2006 Chgr R/T R&T that I swapped the rear end to one from an SRT (3.06 ratio). I will be selling this car but want to keep my Predator for use in the 2006 SRT I just bought! I need to reset the axle ratio in the R/T to 3.06 so the car's new owner doesn't need to rely on the Predator. They may not even know what it is. Reprogramming the ratio has got to be a simple thing since the Predator does it so quickly but I haven't found a Dodge service tech that knows which module to update using their StarScan, etc. Can anyone help me get this done? Are there any Dodge/Chrysler techs that have done this at their dealership? I just need instructions on which module to update and which menus to access in what order. Thanks!

U7135 running 9r12 Crom

[mikel]

If you use the pred to set the axle ratio in that car, it will be married to that car, and will not be able ot be used in the 2nd car without paying $129 to unlock it.

[rodneyiii]

If you use the pred to set the axle ratio in that car, it will be married to that car, and will not be able ot be used in the 2nd car without paying $129 to unlock it.

I know that. That is why I am asking how the Dodge dealer can modify the ratio so it will be a "factory" setting.

[rodneyiii]

Which module is being updated by the Quick Adjust for axle ratio - ECM,TCM or FCM?
How about for the Shift Firmness?

Thanks.

[mikel]

We only talk to the PCM in these cars.

[rodneyiii]

We only talk to the PCM in these cars.

I'm confused. If the tire size & axle ratio data is stored in the FCM, what is changing in the PCM to affect those parameters?

[mikel]

We only talk to the PCM in these cars.

I'm confused. If the tire size & axle ratio data is stored in the FCM, what is changing in the PCM to affect those parameters?

Who said it was in the FCM?

If you think about it, we are able to change shift points in the 05-07 models, yet we dont talk to the TCM either...

Things like what shift points to use, and gear ratio, tire size (anything you see under quick adjusts) is not part of the tune in the PCM, but it is part of the PCM file.

[rodneyiii]

Who said it was in the FCM?

The '06 Charger service manual. Without changing the gear ratio, my car's tranny throws a P0733 code which is "Gear ratio error in 3rd". When that happens, the service manual says to check the pinion factor in the FCM to verify that it is set properly for the actual tire size and axle ratio in the vehicle. The only place "tire size" is asked for is in the FCM StarScan or WiTech menus. The gear ratio error stuff starts in section 21, pg 49 of the service manual.
Next, how is tranny line pressure for increased shift firmness adjusted without tapping the TCM? How about resetting the TCM shift adaptation?

[mikel]

I cant really explain all of that to you...but the 'shift firmness' is not line pressure at all, and things are not as they appear on the surface....

[rodneyiii]

I cant really explain all of that to you...but the 'shift firmness' is not line pressure at all, and things are not as they appear on the surface....

I get what you are "not " saying. After all, you don't want to give away all your secrets. That's how you guys make money.
One more question about the $129 unlock option you mentioned earlier. If I was to quick adjust the axle ratio in my car and get the Predator unlocked, will that new ratio change be permanent? For example, if the car's new owner had the dealer reflash the PCM, would that axle ratio be overwritten with the OEM info? TSB flashes indicate that the module's code is "selectively" reprogrammed which seems to indicate that certain parameters are left unaltered. I would hate to potentially screw up a future owner's repair job and have the shop go nuts trying to figure out why the tranny kept going into limp-in mode.