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Thread: Flashscan V2 J1939?

  1. #1
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    Default Flashscan V2 J1939?

    I have a 2000 T-444E navistar. that i retro-fitted an allison 1000 6 speed (A41 TCM, J1939 throttle), to run standalone..

    all is good i can tune the TCM .. and im slowly learning how to dial in my transmission.. there are a lot of unknowns... like changing my speedo parameters in EFILive makes no difference in the pin 25 output.. (not sure why?)..

    anyway I also have an A53 TCM that i lknow I cannot tune with EFI, it is also J1939 throttle, etc.. however I was thinking I should be able to read the live PID's. in scan mode? but I cannot do that.. I can read them on the A41 TCM.. trying to figure out why I cannot with the A53. (not talking tuning but reading the PID data)..

    if I switch my flashcan to J1939 it seems I get a lot of "this feature not available in J1939".. so im kind of lost as to what J1939 does in the flashscan...

    is there something i need to flash into my flashscan V2 before I can read J1939 with it?

    -Christopher

  2. #2
    Forum tyhee Site Admin GMPX's Avatar
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    J1939 is for the new 'red' HD V2 Flashscan's only.
    Need official EFILive help, please go here.
    For tuning support please post your questions on this forum (or other auto forums).
    Sorry if I don't respond to your PM, don't take it personal.


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    what red HD flashcans? did I buy the wrong one? i just bought my flashcan V2 about a month ago or less maybe.. did I buy an old version when I copuldve or shouldve had a newer revised one?
    -Christopher

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    also help me to understand... my current flashcan reads data from my A41 J1939 enabled TCM... meaning the TPS is running J1939 from its analog to digital box into the TCM.. its on the same CAN 1 wires as the flashscan is connected.... is that not J1939 data there? or is it a mixture of protocols going on there with J1850 and the TPS is sending J1939 as well?

    im a bit confused... i havent stuck a true J1939 scanner on those wires yet to see if I get J1939 PGNs or not.. but it seems I would..

    -Christopher

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    The Axx Allision TCM's have J1939 outputs too for communication with J1939 modules, but in LD automotive situations they can be read and flashed via the 500K CAN port (the one on the OBD-II plug, J2284 spec), there is no J1939 comms on that port.
    Last edited by GMPX; August 13th, 2017 at 02:37 PM.
    Need official EFILive help, please go here.
    For tuning support please post your questions on this forum (or other auto forums).
    Sorry if I don't respond to your PM, don't take it personal.


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    see im a bit confused.. the TCM's i hgave accept J1939 input for throttle through the CAN 1. pins on the TCM, butthose pins are also where an OBD-II plug was installed in my harness and I tune my A41 this way (and read its data).. from what i can tell in OEM medium duty applications for the TCM's. those same pins are where the OEM J1939 feed from the ECM would go. which is ultimately what im working towards.. im just trying to figure out what PGN / SPN pairs are being sent.. therefore wanting to read J1939 with my flashscan.. perhaps the CAN ports are usiong both spec's

    im in a Medium duty environment with J1939 throttle TCMs (an A41(EFIlive does talk to) and an A53(which EFIlive wont talk to)) ..

    -Christopher

  7. #7
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    I run A41s on 7.3 powerstrokes with analog throttle input, but I do know a couple things, CAN 1 is J1939 canbus, and CAN 2 is 500K GMLAN canbus spec. I've ALWAYS been able to connect with the correct harness. I have BOTH can connections wired into my truck, Can 1 to a 9 pin Deutch HD connector, and CAN 2 into my OBD2 connector for EFI live. I also have set up TCMs on engines that listen to SEM requests on J1939 and you HAVE to use CAN 1 connections for that, so if you're feeding throttle from the T444E ECM into your CAN 2 GMLAN OBD2 can lines (That EFI live can connect to) I don't see the TCM actually picking up the messages, and I bet it's just estimating TPS (Which it will do) and that's probably wreaking hell on your shift scheduling. Feed your throttle into CAN 1, and connect EFI Live to CAN 2 and I bet it will solve your issues.

    Oh, and I'd love a copy of your A41 J1939 throttle cal and If you want my analog throttle cal I'd be glad to send it your way too!

    Here is your CAN connection pinouts and wiring
    Click image for larger version. 

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    I have both CANs wired up same as you.. an OBD connector on my CAN2. and my CAN1 is connected into the J1939 database

    im running my J1939 into my CAN1 and verify with EFI plugged into CAN2 that the comms is good.. my TPS reading on the Navistar side matches exactly the TCM TPS readings so all is good there.. when I operate cruise control mode the TCM receives the Engine Load factor as TPS and it matches Navistar perfectly.. that thread I posted previous was almost 3 years ago I have learned a lot since then..

    one thing I learned is that the ECM itself on my engine was an 00. and the J1939 to trans integration in the core software of it sucked.. and it wasnt somethuing that got updated when I ran it through NavKal and did an update form Navistar.. I bought a used 2004 Year ECM and programmed it for my VIN, and wa-la the J1939 implementation worked so much better..

    my thing now is I wish i could add datapoint "wires" to TCMs so i could enable Tapshift... I have an A51 TCM with it in which Tap shift via J1939 is enabled and works when I send it the correct PGN / SPN.. however I cant edit the Cal on it and its WAYYY off from what i need.. EFI wont touch it, and I havent found any Allison software that will.. I have DOC And winrw32 but those wont allow the ability to edit calibrations.. no idea how to get that..

    my A41 I can see the Tap request in the OBD2 datapoint PIDs go active but the TCM never changes range so the datapoint wire in my A41 isnt enabled.. which matches what I read out of it with DOC.

    what format do you want my J1939 Cal? EFILive or a dump of the TCM from winrw32?

    -Christopher

  9. #9
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    I'm looking at some cals in hex to see if I can find the input enables, I'll post up a CAX file for you if I can figure it out!

    Send it to me in both formats if you want, I'll send you mine back. - lawrence at shaferdiesel.com

    Too bad we cant copy an OS definition and change a few things in it to try unsupported TCM/OS's, I was almost gonna see if I could figure it out until I remembered they're all encrypted and we cant see jack shit in them lol.

  10. #10
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    so the CAX files are EFI files or are those the parameters in Allison format? seems to add inputs we need to be able to get that them on the Allison side? who holds the magic software that is used to actually build calibrations? is that something only done in the allison factory? it seems like even dealers cant edit base calibrations on TCMs?

    I have a book which tells me what each "wire" in the IO does and even when to use them. but of course no software to acrtually add them or delete them.. I have played with sending various J1939 messages to and from my TCM, moist of them actually work on my A51 TCM but the shift schedule is WAY-OFF on that one as my throttle map brings the power in early and isnt linear so its easy to lug the engine with that TCM and i cant tune it in EFI..

    on Navistar electronic diesel engines the throttle pedal is essentially a "cruise control" of sorts for the engine.. so for instance if I press the pedal down 20% TPS the engine is going to try and reach 1700 RPM.. it will fuel heavily to do so. its progressive but essentially if im more than 500 lower than that 1700 its going to fuel it to 100% load factor.. as you get lower than 500 RPM away from set poiint it reduces the fueling.. im guessing this is the way the ford 7.3 / 6.0 work as well, however not sure on the duramaxx if they use a similar strategy or not..

    I built a box with a Raspberry PI 3 and 2 J1939 to USB devices which I could "massage" the throttle i sent to the allison to mirror load factoring better, however vehicle speed plays a big part, and the allison uses its own internal Vehicle speed in the TCM for shift points.. well im guessing its simply using the Output shaft speed in the calibrations. as vehicle speed is relative across the board..

    the TAP shift feature may jusdt never have been offered on an A41 TCM.. although it does register it using the PID viewer in EFI. it just doesnt act on it when I sent the appropriate J1939 data..

    I can see extra Datapoint wires added in in my A51 TCM with allison DOC so in that particular CIN its enabled.. my A41 TCM doesnt seem to have a CIN, im guessing because doc really doesnt like its OS anyway.. my A51 does have a real CIN.. I dont have the ability to lookup CINs without an allison login..

    -Christopher

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