97 Tahoe Transmission Shifting Issue

[Wewa Tahoe]

Hey guys I bought my 97 Tahoe 2 door 4x4 about two months. From the day I bought it I've been having this issue. When the engine is cold it shifts hard from 1 to 2 and will not shift into 4. Also it will not downshift into 1 either. It throws a code of P0785 also. But when it warms up to normal temperature I just turn it off wait about 5 seconds, crank it up and everything works fine. The code disappears also. Any help you guys could provide would be greatly appreciated.

Thank you!

 

[derekjl]

I also have the hard 1-2 shift issue. Only happened after replacing the tranny.


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[ccapehartusarmyINF.(ret)]

im going to assume you have a 4l60E
okay a p0785 is a 3-2 downshift solenoid failure

this came from the top 30 4l60E problems these are the closest problems to what your describing
4. 1-2 shift is delayed and harsh, may not shift into OD: TPS needs to be checked for smooth and linear electrical response over the entire range of motion. If not, this must be replaced.


10. Trans shifts into gear harshly, car feels sluggish off the line, No 1st, 4th or TCC lockup available, Manual 2nd, 3rd and Reverse are only available gears, CEL is on: transmission is either in limp-home mode or has lost electrical power. If there are lots of error codes in the PCM, check the underhood fuse that powers the transmission, and if it pops again, look for a short in that circuit like an O2 sensor harness touching exhaust. Otherwise, check PCM codes for a particular fault in the transmission causing the PCM to put it in limp-home mode.

 

[Wewa Tahoe]

Just wanted to update everyone on what I did to fix it in case anyone else runs into this issue. All I had to do was install a new ECM. No more issue after that. Runs like a brand new vehicle.

Thanks for the help. God bless!

 

[SunlitComet]

all you had to do? Hope it works but would love to get hands on that pcm.