Allison Stutter shifting up hard shifting down

Chevman-D

Knuckle buster
Aug 14, 2019
13
0
1
Green Bay WI
I completely reprogramed my ECM with the latest program from GM. I had no choice though because mine was from a newer model with the extra Solinoid in the valve body that mine didn't have. Did a complete relearn not just resetting the values. But it sounds like exactly how mine acted. The kicker is the wiring on these things do sometimes have issues so make sure you check that aswell especially up around the computer it sometimes rubs the harness and also down on the trans the connector pull it and it will get trans fluid in it causing issues. Also, check all your grounds rule out the simple things first. I did my grounds first because they had continuity BUT not great. Granted didn't fix it but don't hurt to make sure. Also check and make sure non of the pins are pushed back in the connector at the TCM this too can cause issues. Are you getting any codes? Do you have a good scanner to get the codes that do not set the Check engine light?
 

dirty_max

Member
Jan 27, 2013
815
2
18
eureka il
I completely reprogramed my ECM with the latest program from GM. I had no choice though because mine was from a newer model with the extra Solinoid in the valve body that mine didn't have. Did a complete relearn not just resetting the values. But it sounds like exactly how mine acted. The kicker is the wiring on these things do sometimes have issues so make sure you check that aswell especially up around the computer it sometimes rubs the harness and also down on the trans the connector pull it and it will get trans fluid in it causing issues. Also, check all your grounds rule out the simple things first. I did my grounds first because they had continuity BUT not great. Granted didn't fix it but don't hurt to make sure. Also check and make sure non of the pins are pushed back in the connector at the TCM this too can cause issues. Are you getting any codes? Do you have a good scanner to get the codes that do not set the Check engine light?

I have a cts on the truck and i'm not seeing any codes or lights on the dash. I do have a v2 with the software on my laptop i can hook up. Im almost convinced it's electrical. I did a relearn on it through the cts and it didnt seem to do anything. Parked it for 2 days and then all of a sudden it was fine. Parked it for a couple days again, took it out for about a 30 minute drive, most of that at highway speed, when i went to slow down to take my turn it started acting up again. Drove it around running errands most of the night and it would be fine for a bit then go back to acting up again. Thanks for the help, when i get some more time i will get it into the garage and look at it.
 

Chevman-D

Knuckle buster
Aug 14, 2019
13
0
1
Green Bay WI
Sounds like exactly what mine was doing. Work then not back and forth. I would only get a code every now and then. Had the spare swapped it programmed it and it started working. Knock on wood still going strong.
 

dirty_max

Member
Jan 27, 2013
815
2
18
eureka il
Now it's gotten more complicated. Went into what i thought was limp mode the other night. Now when i put it in any gear the indicator flashes at me and it wont move. I had a code on the cts. Just a p0700 but i erased the code before i could check it with a good code reader. Thought it was just in limp mode because it wouldn't move in reverse. Now it moves in no gears
 

dirty_max

Member
Jan 27, 2013
815
2
18
eureka il
Tried a tcm i had laying there and still the same thing. Pulled the spin on filter and there was no excessive debris on the magnet. Pulled the pan down to check the internal filter and it was still up in there. There was some red flakes in the bottom of the pan that i thought was clutch material. But the fluid was all clean.
 

dirty_max

Member
Jan 27, 2013
815
2
18
eureka il
just thought I would update. I found that my issue is internal. I have a clutch that is delaminating. had the valve apart and it was full of clutch material.
 

Chevman-D

Knuckle buster
Aug 14, 2019
13
0
1
Green Bay WI
That's an interesting one but at least another solution to a similar problem. Hopefully, this keeps helping other people out there chasing the rabbit.