So I got this 1997 s10 blazer for a buck and I got it running. The owner said that there was a tranny problem with the vehicle but she could not tell me what it was doing. So once i got the blazer running the tranny worked find so i decided to put new filters in the tranny and fluid. well thats whats i did today and it was a pain. so i took my new ride for a test run to get the tranny worm and when it shifts into 3rd gear it slips really bad and will not catch that gear. so if my tranny bad or is it a sensor. also i used a snap on tester to see if there was any codes coming from the tranny and nothing showed up. so whats going on with me tranny

 

A bad 2-3 shift solenoid could cause it not to shift into 3rd, but it shouldn't cause it to slip when in 3rd.

 

no when it trys to shift into 3rd gear it wont and the engine will rev

 

So it revs just like it is still in 2nd? If so, then it definitely sounds like a bad 2-3 shift solenoid.

 

when ur in second gear and its ready to shift to third u can fill it shift and then it revs