MY blazer shifts fine up, but when it gets to 3rd its like its locked out, and if i step on the gas harder it downshifts back to second. I don't think my transmission went out but I don't know what else it could be.

 

Thats crazy

 

sounds like a solenoid.

 

what do you mean, locked out? Do you mean it wont shift to 3rd and fourth or just wont go to fourth?

 

I would have to agree with the above post. Usually a shift problem like that is caused from a faulty solenoid, though it could be from not having enough fluid but usually that causes a slip not a full on shift problem.

 

a selinoid shifts up and another shifts down... sounds like its faulty.