99 Blazer 4L60E Tranny Issue
 

Backstory: I inherited a fix-it project from a friend. He said it was leaking a lot of fluid so he had it towed to a GoodYear and inspected. They said there was an oil leak at the rear main seal and quoted like $1200 for the job. Once I inherited the project, I lifted it up and checked for said leaks. Engine oil was still full. I cranked the engine, no leaks at all. I noticed a drip of transmission fluid hanging at the bellhousing. I'm assuming Goodyear automatically assumed this was engine oil coming from the rear main seal but it was actually transmission fluid. I check the trans fluid level and I noticed that it's actually overfilled.

So while the vehicle is in the air, I shift through all the gears. All gears seem to output power except reverse. Reverse only made the wheels spin when giving a little more gas. I drain some of the fluid to operating level since it was overfilled and drop the car back down thinking the car will be able to drive. Once on the ground I shifted into gear and the vehicle won't move in any gear. The shift lever is able to move into all gears but the vehicle just wouldn't move.

So what would cause the wheels to be able to turn with no resistance, but not be able to turn when the car is on the ground? Bad TC? Bad Pump? If it's able to shift in the air, then that should mean the solenoids are working properly right?

Did you get an answer to your transmission slippage problem? I have a similar problem

The trans was toast. I replaced both the trans and torque converter completely.