Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: 4L80E TCC AppEn Mode

  1. #1
    Lifetime Member
    Join Date
    Mar 2007
    Posts
    349

    Default 4L80E TCC AppEn Mode

    Been playing with an '01 K2500 6L 4L80E Silverado. Quick question though, after reading some of joecar's excellent technical info, I am still wondering just what AppEn is and how to control it. From reading, I would guess that this is simply the TCC "slightly" turned on (i.e. dragging). As to what controls it, it appears that this happens anytime the transmission is in 2nd - 4th gear (never seen it kick in in 1st gear) and certain TCC Slip (RPM) values are not exceeded.

    The reason I am trying to understand this is for two reasons. The first is that my dad's truck (99' same configuration except with 3.73's not 4.10's like the '01) seems to hunt a lot between Off and AppEn during 2nd - 4th gear. I would really like to either turn it on, or turn it off so it doesn't keep hunting. The second reason is that for this '01, we are kicking around swapping out the 4.10's for either 3.73's (could be the same problem that my dad's truck has) or even 3.55's (he doesn't tow much so MPG is more important). I have a gut feeling that if we go 3.55's that the '01 will hunt even more.

    So far, I have logged data and figured out that if the TCC Slip (RPM) gets too high, then it kicks out. Didn't know if anyone else had played with or experience dealing with this condition.

  2. #2
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    AppEn is 4L60E terminology...

    I'm not sure what AppEn means for the 4L80E since it has only the TCC PWM solenoid (i.e. no TCC Enable solenoid like the 4L60E has).

    When TCCMODE is AppEn, the PCM might be ramping the TCC up.

    Log these pids:
    - TSTATE00 (TCC Enable Solenoid, Brake switch)
    - TSTATE01 (TCC clutch status)
    - TSTATE12 (TCC state)
    - TSTATE09 (TCC off reason)
    - TCCDC (%)
    - TCCMODE
    - TCCSLIP
    - TIS
    - TOS

    When you see TCCMODE say AppEn look at TCCDC to see what AppEn means...

    The state bits shown in the TSTATE pids may not apply to the 4L80E, but they might be interesting.

    If the PCM detects excessive TCC slip it may decide to not apply the TCC.

    Post some logs...

  3. #3
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    Hi turbo_blu,

    Make sure D1007,8,9 are set to 100% (otherwise D1001,2,3,4,5,6 may interfere, preventing TCC apply, or causing a TCC transition).

    If you bump up D2903 to be close to D2904 (which should already be above 90%) then the PCM will ramp up the TCC much quicker (i.e. less dragging/slipping during the transition)... you might get some "feel" when it applies, some people don't like this, you would have to try it and see.

    Post your tune file...


  4. #4
    Lifetime Member
    Join Date
    Mar 2007
    Posts
    349

    Default

    joecar -

    Thanks for the thoughts. Here's a few answers to your questions:

    I can say that when AppEn kicks in, that the TCCDC (Duty cycle) stays at 0%. It is only when the actual TCC goes to App then to Lock, that you can see the TCC Duty cycle kick in and ramp up just as you have shown in your 4L80E background information. That part makes sense.

    I already have D1007-9 set to 100% (stock setting)
    D2903 is also stock with D2904 set to 99% (again stock settings).

    I have watched the TCCSlip (RPM) and it appears to change some when it AppEn kicks in. To date, I am going off data logs from my friend and my dad. I hope to borrow my dad's truck soon so I can "play" with it to verify the actual conditions / phenonmenon that are occurring.

    I am attaching a copy of the '99 tune (stock - haven't changed any settings yet). So far, this is the truck that I am learning on.
    Attached Files Attached Files

  5. #5
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    With the 4L60E, from looking over my logs, it seems that TCCMODE going to AppEn means the PCM has turned on the TCC Enable solenoid (now called TCC solenoid) and the TCC PWM solenoid is still off...

    the 4L80E doesn't have the TCC solenoid, so AppEn is just a state the PCM goes thru before commanding TCC PWM.

  6. #6
    Lifetime Member
    Join Date
    Mar 2007
    Posts
    349

    Default

    From what your showing then, there should not be any change to the torque converter when the log shows AppEn. It would be the same as Off.

    I will try and verify this when I get a chance to do some more logging on my dad's truck.

  7. #7
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    Ok, I looked more carefully at some old and new logs and this is what I saw on my 4L60E:

    when TCCMODE is AppEn the PCM momentarily cycles TCCDC to 97% with the TCC Enable solenoid OFF (i.e. TCC is not applied).

    then this is usually followed by TCCMODE App where I see TCCDC drop to 10-12% and then TCC Enable solenoid goes to ON, and then TCCDC is ramped up to 97% (i.e. TCC is now applied).

  8. #8
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    Post some logs of your 4L80E...

    It seems to me that at AppEn your TCC would still be off.

  9. #9
    Lifetime Member
    Join Date
    Mar 2007
    Posts
    349

    Default

    Here's a copy of one of the data logs from the '99.

    You can watch the AppEn kick in and out and then later on the TCC finally goes to App and Lock.
    Attached Files Attached Files

  10. #10
    Lifetime Member
    Join Date
    Mar 2007
    Posts
    349

    Default

    Finally got a chance to go and drive my dad's 99'. Here is a segment of data showing the AppEn kicking in and out.

    After looking at this for a while, I had a brain fart. Wonder if GM did a good thing for us??? Guessing that they used the exact same code on the 4L80E and on the 4L60E's and other trannys. Thus in the code itself, it IS commanding AppEn and thus we are reading it with EFIScan (or BBL'ing), BUT, the reality is that this is doing nothing since the tranny doesn't have anything hooked up to this particular pin / circuit.
    Attached Files Attached Files

Page 1 of 2 12 LastLast

Similar Threads

  1. 4l80e question
    By aaronr in forum 4speed RWD/FWD Transmission Tuning (incl T42)
    Replies: 2
    Last Post: December 19th, 2009, 04:44 PM
  2. 4l80e help
    By da69fishman in forum 4speed RWD/FWD Transmission Tuning (incl T42)
    Replies: 6
    Last Post: December 9th, 2008, 11:21 PM
  3. L76 4L80e AFM
    By 4wheelin in forum E37, E38 & E67 PFI ECM's
    Replies: 34
    Last Post: November 24th, 2008, 10:04 AM
  4. 4l60e ---> 4l80e What changes ?
    By Tydriver in forum 4speed RWD/FWD Transmission Tuning (incl T42)
    Replies: 1
    Last Post: March 2nd, 2006, 01:40 PM
  5. Can Valet mode be used to turn SD mode off and on?
    By ForcedC5 in forum General (Petrol, Gas, Ethanol)
    Replies: 5
    Last Post: May 17th, 2005, 10:53 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •