2005 5.3 1500 Sierra Tranny Issues, Help PLZ

[lmcurto]

recently I had my 2005 GMC Sierra 1500's transmission flushed and refilled, the mechanics didnt see anything wrong, no metal shavings, no nothing, well starting off it will lurch forward at times, others its smooth, and then once the spedometer reaches ~30mph, the rpms go sky high and overdrive wont engage out of 3rd gear, if I press down on the accelerator pedal the rpms will go higher, almost sounds like its in neutral, and eventually it will finally kick into overdrive, and sometimes it wont, after I go through this initial mess, the truck has no further problems driving around town until I turn off the engine, then once I start off again I get the joy of going through the same headaches until the overdrive will finally kick in that first time then everything is all hunky dory, it seems like something is sticking possibly but after that first stick is released, runs fine, can someone please help in any advice on what I should look at, I'm hoping that I dont have to have the transmission rebuilt but any advice would be greatly appreciated in figuring out whats going on with my truck, thanks

update> today at lunch I was returning back to work and now it wont shift at all above 2nd gear, once its in 2nd gear, anything over 30 mph the rpms just go sky high, even pressing down on the accelerator it wont shift at all, please help anyone

 

[Molson02536]

recently I had my 2005 GMC Sierra 1500's transmission flushed and refilled, the mechanics didnt see anything wrong, no metal shavings, no nothing, well starting off it will lurch forward at times, others its smooth, and then once the spedometer reaches ~30mph, the rpms go sky high and overdrive wont engage out of 3rd gear, if I press down on the accelerator pedal the rpms will go higher, almost sounds like its in neutral, and eventually it will finally kick into overdrive, and sometimes it wont, after I go through this initial mess, the truck has no further problems driving around town until I turn off the engine, then once I start off again I get the joy of going through the same headaches until the overdrive will finally kick in that first time then everything is all hunky dory, it seems like something is sticking possibly but after that first stick is released, runs fine, can someone please help in any advice on what I should look at, I'm hoping that I dont have to have the transmission rebuilt but any advice would be greatly appreciated in figuring out whats going on with my truck, thanks

update> today at lunch I was returning back to work and now it wont shift at all above 2nd gear, once its in 2nd gear, anything over 30 mph the rpms just go sky high, even pressing down on the accelerator it wont shift at all, please help anyone

Your going to have to take it to a transmission shop and have them scan the transmission for a Tech2 scanner. It might be as simple as ShiftA solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.

Good luck and keep us posted.

 

[Z15]

How is the fluid level? How did they flush it, with a machine or use the purge method, e.g. open a cooler line and run engine to pump old atf while adding to the filler pipe?