Thanks, I am also concerned about the solenoid, and im hoping it’s not the torque converter itself. No abnormal sounds from transmission.

The transmission fluid level I described was showing at least a half inch above the high mark (XXXXX) for every reading taken. This was immediately after a 45 minute drive, on a level surface, while still idling.

 

From what I’ve researched... Some trucks experiencing these symptoms have a worn bore in the valve body where the TC solenoid is located, allowing fluid to pass through.

Is a valve body hard to remove? I may just purchase a new body with new solenoids already installed . Could this be too difficult for me to replace the valve body? Im no expert but I try to do work myself to save on costs. I am assuming the transmission itself does not have to be removed

 

I had the same problem on my 2009 5.3. I bought the truck used from Chevy and bought an extended warrantee. I brought it back for the same problem your having. They Changed the torque converter, didn't fix the problem. They gave up, didn't know how to fix the problem. So I went to my transmission guy. He knew right away what the problem was. He rebuilt the valve body, installed new seats in the pressure check valves. Not to expensive a job and the extended warrantee paid for the job, The $100 deductible was paid buy Chevrolet. I think the steel seats make the trans better that new. Instead of the check valve ball seating in aluminum it's now steel and won't wear out . What the heck does Chevy think will happen? Had the same thing done to my 2006. Both trucks worked great after this fix. To bad I cracked up the 2006.

 

I have the same exact problem with my 08 Avalanche. I had a reman trans installed after 3rd and 4th went out at about 122K miles. After the install I noticed it doing the fluctuating when cold. After it got up to temp it didn’t fluctuate any more until the next day when it was cold. About 5 months later the trans line blew and took out 3 and 4th again. I had that trans rebuilt again and after installing it and driving it did the same fluctuating as with the first rebuild. Did you ever figure out what was causing the issue? Thanks

 

Never "rebuild" transmissions. They always fail. Get an off-the-shelf remanufactured and dyno tested unit with warranty.

 

Ever get your RPM fluctation figured out?...having same problem with 99 Silverado.