been a bit since i updated,, lotsa miles, lotsa trips.. and I **FINALLY** solved the no-downshifts on cruise control issue..
it seems i wasnt the only one running allison 1000 or 2000 transmissions that would lug the engine wayyyyy down before downshifting in cruise-control mode..
ultimately a few pages back you all will note the J1939 data that I posted..
I finally tried to flash my ECM to a later VIN number and found it would crash during the procedure, brick the computer, and id reload from scratch,..
I was damn determined to figure out what the deal is..
so I ordered a "new" ECM on Flea-bay from a 2004 T-444E. the new ECM arrived, I plugged it in and damn the thing would start the engine but the speedometer just read 100 MPH... so I plugged in the laptop and found that I couldnt flash any parameters without getting an error # 8, cannot reprogram..
booted up NavKal and tried to Flash it blank (I have a valid NavKal subscription so i can download the latest firmware from Navistar and re-flash any ECM).. no -go...
write the seller on ebay and of course his reponse was "we pulled it out of a working truck, but the WARN light was on.. some guy tried to plug his computer in and didnt have a clue.. so we parted out the truck.. someone wanted the engine anyway..."... great..
well why not.. I pay $$$ for that navistar subscription.. I called navistar and said "i have this error 8.. and wierd speedo stuff".. he remoted into his computer, loaded servicemaxx into his "god mode" and still couldnt flash it.. then he remembered a bug in their code that if the speed sensor inoput was set to J1939 it bricks the ECM because the speed goes to 100 in absence of a valid J1939 speed sensor.. so if someone changes that setting by accident.. the WARN light comes on and the speedo pegs out..
there is no way to change it because of the built in "safety" that says you cant reprogram a truck that is still moving.....
he read off an email to me that stated the customer must send the ECM to navistar and Tier-III engineering puts it in their system and can re-flash it..
so i asked if simply put it was looking for a J1939 message that says '0 MPH'.. "maybe?? im not the one who wrote that email... sounds possible?"
so I went to work!.
the J1939 Spec states that vehicle speed is sent in PGN-65265.. this PGN sends 8 characters.. or 8 sets of 2 Hex "digits" in 8 bit.. bytes 2 and 3 are vehicle speed...
Screen Shot 2019-03-27 at 8.44.32 PM.jpg
you send FF for anything you dont want to support..
so I decided I would send F1 00 00 00 00 00 00 FF
which tells the computer im sendinfg the data to that my cruise is turned off and my truck is going 0 MPH..
so now next hurdle is what do i want my identity to be on the network.. on J1939 each module or computer has an identity.. and you claim your identity..
I surmised since my transmission is identity 3 and sends through this datas already.. (spoeed still reads 100).. that the engine ignores data from address 3.. and besides the tranny layed claims to it..
address 1 is the main engine computer..
so I can be anything else.. but really I need to figiure out what kinds of things can send vehicle speed back to the engine..
we ruled out the tranny.. ABS modules? yep they can.. and I scoured the internet and found that Navistar either told venord to make their ABS modules 11 or 17.. meaning thats the Address they claim..
so I fired up my J1939 injector / simulator and set up as address 17 and sent the above data through... nope!! nada nothing!!.. I reset and claimed address 11.. as soon as I set the claim I noticed my Servicemaxx software on one of. the laptops instantly displayed that an ABS controller had come online!! at address 11.. I sent that data through once and my speedo blippeed downward for a few 10ths of a second.... yes I knew I had the right data.. now to make it repeatable..
reading the Spec I posted above you can see that the Parameter Group we are using is supposed to be repeated every 100 milliseconds.. or 10 times / second... so I set my simulator up to send it 10X and off it went.. and my speedo dropped to 0, the WARN light went dark and all DTC's cleared..
essentially my engine computer thought a real ABS controller was sending data to it.. and says "Ok cool!"..
I reprogrammed the parameter to the correct value.. "hardwire OSS" yeah it saved perfectly... then I reloaded all the latest greatest software into it from navistar....
plugged everybody in ..took a ride down the highway.. set cruise control.. and low and behold my allison Now downshifts properly on electronic cruise!!!.. go up a hill..engine lugs... speed drops 2 MPH and bam down a gear we go!! climb a steeper hill..bus starts to slow down... bam down to 4... just like clockwork...
the cruise still seems to fuel the engine a bit slow.. but i learned there are new throttle maps for that.. i just gotta set one up and play..
yeah!!!! Cheap ECM.. guys that have no clue.. and no $$$ soent with navistar.. almost 2 year old issue solved!!!
oh I also noticed the engine runs smoother and quieter with the new ECM... so if you have an older T-444E, you may want to look into a newer ECM for it..
Part number for the lates is 1833558C3. but they are hard to find... the nearly latest is 1833558C2..
took a 200 mile roadtrip yesterday.. and busted a dam,n idler pulley... luckily just for the Transair.. the belt layed itself right across the engine fan... since i have a horton clutch my fan was easily stopped by the belt as it was just free-wheeling on a 45 degree day..
we had a Blast school bus Junk-yarding!!!!
Photo credit for this last one is Jim Ross.
new idler pulley is on order and ill have my A/C fixed before I ever think about turning it on..