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I believe different for the Allison, but it may start, probably set codes for no Auto but easy to clear. You have seemed to rule out issues with the harness and connectors.I would swap the VECU first and try to start, than go the next. If it starts puul the first unit you put in ,reinstall the original and see if it starts. Extra work but you can sort of end up replacing only the bad unit. You did check the harness plugs and modules for corrosion at the connector pins, didn't you?
You may lose the clutch shortly. Usually when that happens it puts enough strain on the clutch and it weakens the friction disks. I had a 6 spd years ago loosen up and about 10,000 miles later the clutch blew. Also I'd replace the bell housing.
So I've been having this issue where my clutch is not maintaining adjustment. Started the other day as I was limping it home (front diff issues...done got another new one of those now)...the dadgum thing instead of having a little free play got to where it was stupid tight...as in it was completely disengaged before it would trip the clutch switch. I adjusted it to get it down to the local Mack (they put in another ReMack front diff) and I asked them to look at the clutch. "Nothing we can see wrong with it" they said.
So today, I'm running and the clutch is gradually tightening up again. So, I adjusted it again at my 1st drop before heading on down the road to grab my backhaul. I noticed a couple bolts missing between the clutch and transmission...odd...but didn't really dawn on me. Anyway, clutch was snugging up some more on my way home, so I got under it with the creeper and found my problem. I've only got 4 bolts left holding the transmission to the bell housing...2 on the passenger side, and 2 at the bottom. I tried moving one of the bottom bolts to the driver's side, but apparently those holes are a little sloppy. Pretty sure the bolts are M10x35 1.25 pitch...was going to see about picking up some more to replace the missing bolts, but now think I'll have to see if I can't find M12 in a 1.25 pitch to re-tap the holes a little larger. If that won't work, I'll have to see about those helicoil things to repair the threads to the proper size.
Anyway, snugged up the bolts and it pulled the transmission back up tight to the bell housing, and wouldn't you know the clutch pedal had about 60% free play? So, I had to adjust it back again to set it right. At least now I know if the clutch starts seeming like it's not maintaining adjustment, that I need to crawl under there with my 15mm wrench and snug it up again to get it back where it needs to be. Hopefully it gets me to the weekend where I'll have a couple days to see what I can do to fix it proper.
Hey bro have you had Much to do with M drive?
We did a clutch replace/ absolutely, everything the flyweel , clutch , actuator and valve the clutch will not calibrate there are no leaks. yet the computor says the clutch is operating to slow makes a hell of a chatter when you try to test it manually via VCADS then that error comes up! To top it off there were no actuators in the system we had to go to another dealer to get one makes me suspicious they a having issues with these and are not saying !