8.1L suburban
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After fully warmed and trans at about 150 or 160 it shifts hard into 2nd am 3rd anyone experience this it's a 2004 2500 4x4 suburban w 8.1L and 145k miles
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4L80e hard shifting issues
- Thread starter 8.1L suburban
- Start date
MrMarty51
Well-Known Member
I aint a transmission specialist but, welcome to the truckstop.
First thing, if it were Me, would be to check all the grounds, make sure that the terminals and grounding surfaces are bright, shiny and clean. As insignificant as grounds may seem, on these units, a poor ground can wreak havoc with all kinds of symptoms.
Probably be some more in the know will come in and reply with some other possible fixes.
First thing, if it were Me, would be to check all the grounds, make sure that the terminals and grounding surfaces are bright, shiny and clean. As insignificant as grounds may seem, on these units, a poor ground can wreak havoc with all kinds of symptoms.
Probably be some more in the know will come in and reply with some other possible fixes.
ak diesel driver
6.5 driver
After that would be to get a scanner on it
8.1L suburban
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Already plugged in the OBD2.... P0894 I believe said said component in transmission slipping. Which is very generic and could be a number of things I'm replacing the trans and transfer speed sensors today.
Husker6.5
135' diagonal 16:9HD, 25KW sound!
Sounds like it could be an A B shift solenoid issue, but the real expert on all things transmission on here is @THEFERMANATOR .
Rockabillyrat
SlIgHtLy StUpId.
Yep P0894 is a slip code. The PCM is calculating the gear ratio by monitoring the input and output RPM of the transmission. If it sees a gear ratio that doesn't match what that selected gear should be it sets the p0894. So basically when it slips the input RPM is higher than desired and the transmission knows there is an internal issue.
If it shifts fine cold but has issues when warm and is setting a p0894. Then you more than likely have a internal issue and need to replace or rebuild your transmission.
If it shifts fine cold but has issues when warm and is setting a p0894. Then you more than likely have a internal issue and need to replace or rebuild your transmission.
- Staff
- #7
1st off, you don't have a 4l80e. 8.1's and DURAMAX's with a 4 speed auto(except 02 6500's) got the ever so rare 4l85e rpo mn8. It's a very similar trans, but you should keep it in mind when getting parts because there is some differences. I doubt it's a speed sensor issue. Thing's that jump out to me would be a bad filter seal sucking air when the fluid thins out, transfer case on it's way out from pump rub, or internal trans issues(direct clutch is probably toast). Check your freeze frame data and see when the code was set. Find the conditions and replicate them with a scanner hooked up so you can see what it is seeing. And the PCM is going to go into limp mode when a slippage code is detected. When this happens it will go to max line pressure, disable torque converter lock-up, and in many times disable 4th. I would avoid driving with it in limp mode because line pressure can spike to SCARY level's (some have seen 500+) which can shatter hard parts.