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Thread: Tshift pid

  1. #1
    Junior Member
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    Default Tshift pid

    I've been doing some data logging on my 4l80e on with the TSHIFT PID as one of the channels I'm collecting data for - mainly just to verify that the momentary ground switch for performance mode was working but it's lead to a few questions about this PID:

    Is there an explanation of the shift pattern codes for this PID that I haven't managed to find yet? When I look at the PID with the V8 scan and tune tool it gives the following list:
    G1Hold - I'm guessing this is Gear 1 hold?
    G2Hold - Gear 2 hold?
    HotKDn - Hot mode kickdown?
    HotNorm - Hot Mode Normal
    Kickdown - Obvious?
    CCSh - Cruise Control shift mode?
    NormSh - Normal shift mode
    PerfSh - Performance shift mode
    PerfKDn - Performance Kickdown shift?
    4WDLow - Obvious?
    4WDKDn - 4WD kickdown shift?

    My application is a 98 Savana van converted to 4WD with an L31/4L80e/USgear20%underdrive/NP205 running an '01 Express (0411) PCM and the '02 Express van tune. I'm seeing a couple things not in the list above show up in the TSHIFT data and am hoping someone can elaborate on these:

    Dtnt ? I'm acronym challenged here, anyone have an idea what this means?
    Perf1
    Perf2
    I'm wondering if Perf1 and 2 correlate to PerfSh and PerfKDn?

    When I shift the transfercase into low range I'm guessing I should see 4WDLow show up in the PID data, correct? It doesn't and seems stuck in 1st gear while in low range, so I probably need to re-visit some of the posts about getting 4low to work, it seemed like there were some segment swaps that fixed this IIRC.

    Also the shift rails on my NP205 are modified slightly to allow a 2WD Low range delivering power to the rear axle only, assuming I should get some indication of low range on the TSHIFT PID, will the low range and 4WD switches both need to be made for the PID to change to 4WDLow? Internally the NP205 has one shift rail for Hi/Low and one for 2/4WD operation and I installed switches on both rails.

    Thanks for helping a newbie out.

    Mark

  2. #2
    Joe (Moderator) joecar's Avatar
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    Default

    Hi Mark,

    DTNT = detent, on most GM transmissions this is kickdown.

    PERF1/PERF2: I'm not sure, but they are not PERFSH/PERFKDN.
    Last edited by joecar; July 18th, 2016 at 06:43 AM. Reason: corrected spelling of "detent"

  3. #3
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    Default

    Hi Joe,
    Thanks for your response. After looking through some more of the data I've collected I have come to the following conclusions: Perf1 - when I trigger the momentary ground switch for "performance mode" this is what shows up in the log file under for the TSHIFT PID. Perf2 - this appears to correlate to throttle position, I have D1206 (WOT Shift Mode Upper Threshold) and D1207 (WOT Shift Mode Lower Threshold) both set to 80%, Perf2 shows up in the data for TSHIFT PID whenever the throttle position is above 80% and am driving in "Performance Mode".
    When driving in "Normal Mode" Dtnt appears in the TSHIFT data when the TPS kickdown is active as you state above, I currently have tables D0960, D0961 and D0962 set to 100% across the board so Dtnt shows up at 100% TPS in any gear 1-4.

  4. #4
    Joe (Moderator) joecar's Avatar
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    ( sorry, I spelled detent wrong, I corrected it above )

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