just thought id do some research after my tranny rebuild since i couldnt find this kinda post after 20 mins

Transmission Adaptive Functions

The 4L60-E transmission utilizes a line pressure control system during upshifts to compensate for the normal wear of transmission components. By adjusting the line pressure, the PCM can maintain acceptable transmission shift times. This process is known as "adaptive learning" or "shift adapts" and is similar to the closed loop fuel control system used for the engine.

In order for the powertrain control module (PCM) to perform a "shift adapt," it must first identify if an upshift is acceptable to analyze. For example, upshifts that occur during cycling of the A/C compressor or under extreme throttle changes could cause the PCM to incorrectly adjust line pressure. When an upshift is initiated, a number of contingencies, such as throttle position, transmission temperature, and vehicle speed, are checked in order to determine if the actual shift time is valid to compare to a calibrated desired shift time. If all the contingencies are met during the entire shift, then the shift is considered valid and the adapt function may be utilized if necessary.

Once an adaptable shift is identified, the PCM compares the actual shift time to the desired shift time and calculates the difference between them. This difference is known as the shift error. The actual shift time is determined from the time that the PCM commands the shift to the start of the engine RPM drop initiated by the shift. If the actual shift time is longer than the calibrated desired shift time, a soft feel or slow engagement, then the PCM decreases current to the pressure control (PC) solenoid in order to increase line pressure for the next, same, upshift under identical conditions. If the actual shift time is shorter than the calibrated desired shift time, a firm engagement, then the PCM increases current to the PC solenoid in order to decrease line pressure for the next, same, upshift under identical conditions.

The purpose of the adapt function is to automatically compensate the shift quality for the various vehicle shift control systems. It is a continuous process that will help to maintain optimal shift quality throughout the life of the vehicle.

Clearing Transmission Adaptive Pressure (TAP)
Transmission adaptive pressure (TAP) information is displayed and may be reset using a scan tool.

The adapt function is a feature of the PCM that either adds or subtracts line pressure from a calibrated base line pressure in order to compensate for normal transmission wear. The TAP information is divided into 13 units, called cells. The cells are numbered 4 through 14. Each cell represents a given torque range. TAP cell 4 is the lowest adaptable torque range and TAP cell 14 is the highest adaptable torque range. It is normal for TAP cell values to display zero or negative numbers. This indicates that the PCM has adjusted line pressure at or below the calibrated base line pressure.

Updating TAP information is a learning function of the PCM designed to maintain acceptable shift times.
It is not recommended that TAP information be reset unless one of the following repairs has been made:

Transmission overhaul or replacement
Repair or replacement of an apply or release component, clutch, band, piston, servo
Repair or replacement of a component or assembly which directly affects line pressure

Resetting the TAP values using a scan tool will erase all learned values in all cells. As a result, the PCM will need to relearn TAP values. Transmission performance may be affected as new TAPs are learned. Learning can only take place when the PCM has determined that an acceptable shift has occurred. The PCM must also relearn TAP values if it is replaced.

im not saying dont get it removed all im saying is if your hard on your truck like i am or u live in a cold climate it might be a good thing to have in might save u some money in the long run. as its stated above ^^^^^can reset your TAP with a scan tool, for those who feel like there 1-2, 2-3 shifts are getting sluggish over time get a service done and get it reset hope i didint waste your time with this post

 

Good read!

 

if your really worried about it you could do is log the shift time for each gear/load right after you put in a new tranny... Then put that shift time in your desired shift time tables...

 

So this might explain why my 4l65 had some funny shifts after a fluid flush. After about 100 miles it cleared up.

 

I had mine tuned off after I installed my HD-2 Kit on my 4l60e and I think I might like it better turned on, since I am using a diablo sport, I have 3 tunes on it. 1 with it on and 1 with it off, but 50% of tm on, and last a tune with it on and 100 tm off.

 

Yall do know that adaptive shift learning has nothing to do with TM... it is done by zeroing out the shift times...

 

Yes, that is what I had done when I said turned off meaning changing the shift times to zero.

 

ok, do you also know that if you turn it back on without adjusting the shift times table it will make things worse....

Here is a scenario to consider...

if you reenable the adaptive shift learning (putting the shift times back to stock), your shift kit will mechanically speed up the shift, the computer will interpret that as an error and decrease the tranny pressure to slow down the shift... So if you reenable the adaptive shift learning without adjusting your shift times to match, you will be actually hurting your tranny.... that is why i posted the above, if you want to keep adaptive shift learning you need to log the shift times for every gear/load so you have a decent starting point...

 

I have never had an issue after I installed my shift kit. If it fails early because of decreasing and or increasing pressure, I will have a built tranny installed. I guess I know a lot of people who installed hd-2 kits and never touch the computer and don't have issues. Your logic makes sense to me... I always wondered about it, but never heard anything about it having to be done or you will ruin your tranny.

 

exactly corey thats why i leave my tuning to Mr Charlie Wheatley. get it done right the first time and you shall have no problems.