Thanks @
j91z28d1
I am a little confused by your response. From this one event the other day where the truck was driving along at 50mph and suddenly out of nowhere either engaged the electric drive motor or applied the brakes on its own, you think it could be any one of those things that you mentioned? I replaced the Hybrid battery just about 2 years ago. It also has a new 12v battery and the connections are clean and solid. I love this truck. So quiet, so comfortable. Sure I miss the towing capacity of my 8.1 Suburban but aside from that this Yukon has been such a pleasure to own. I'd liked to repair this issue and keep it on the road.
My gut tells me it may be the electric drive motor that suddenly engaged mainly because of the noise it now makes while just idling in the driveway. I can't think of anything that would cause this sound related to it being a communication error due to voltage flux or absence etc...
I think there is a chance that the sudden braking or violent jerking episode could be related to the active suspension module shorting out and it shutting the system down but I don't think that would cause the rattling noise at idle after like it has now. I already sourced a genuine GM part for the active suspension module and will have that installed but I could really use some direction regarding what else this might be. As of today the truck is angry and does not want to run. It will start and then turn off 2-3 seconds later. Giving an Engine Damage warning
Video of sound now
what I was meaning is I think it shutting off on you a year or so ago could be something different than happened this time. I've never seen an engine damage warning. is that on the dash display? makes me wonder what triggers that warning and how the tranny would make it think the engine is damaged.
man that does sound pretty bad. I might have missed it but how many miles? these transmission seem pretty common to go 250k or more miles.
These trannys are bit of a mystery and no one really rebuilds them. I talked to a retired gm tech that said he went to class for these when they came out. they spent 2 days on the transmission and then said but don't worry about any of that, you won't be rebuilding these. if they are bad gm engineers want them back and will send new ones in.
A used unit seems to be the only real way to get one these days. I've seen some on Facebook market for as low as 600$. they do have 2 electric motors in them, but they run kinda all the time doing different things. I honestly do not know if one could have a issue and lock up the tires like that. the transmission control module is inside the tranny and the shift linked is a cable. so I don't know if a can bus failure could cause this or not, but I'd hazard a guess that it shouldn't be able to. I guess it could have also engaged a lower gear at the wrong time too, like say downshift to 1st while doing 50. but I just don't know enough to say.
These don't have a torque converter like a normal tranny but there is a flex plate type of thing where a fly wheel would go that transfer power from crankshaft to transmission input shaft. maybe it broke that?
if you pull the dipstick and put it on a clean towel, do you see any metal? you could pull the pan and look for metal on the magnet inside too. Just be careful 14qt of fluid all come running out. makes a mess if you're not ready for the amount.
so for the codes, I guess you tried clearing them? did they come back? if so which ones? are you able to communicate with the modules with your scanner right now? what scanner do you have? does it show any live data from the transmission?
sorry, all I have is questions, no real answers. for the short time it's running, have you tried putting it in gear and see if it moves?
I fully understand wanting to keep it. I like mine a lot and since I'm basically a mechanic by trade. I hope I can fix whatever to keep mine going too. and I think I can fix most things, as I've read tons of posts and threads about issues to try and understand what all can go wrong. mine has been pretty solid thankfully, just the normal stuff for this generation and I'm Bata testing a different hybrid battery type right now that seems to be going well so far.
the transmission being the one thing I worry about that I can't fix. I've kept my eye out for a used one local, just to pick up as a spare if the day comes. I have read of some wearing out and slipping, but never once have I seen anyone post anything about one exploding internal like yours might have done.
