Hi everyone this i my first post I have a 2001 high mileage chevy blazer runs amazing but the transmision wont shift into second or fourth, won't even try. It has the classic symptoms of a speed sensor issue (speedometer all over the place, won't shift, and abs light is on) so I replaced the sensor on the top rear of the transfer case but it had no effect at all. Is there a second in the transmision because I cannot find info on it anywhere I'm also not sure if I have a transmission sylonoid out or if I should even try replacing that if the sensor doesn't help. any info would be apreciated. Also i do have a 2004 blazer with a blown headgasket that I can take parts off of
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Sounds like a broken band. Could also be a broken reaction shell but usually have reverse issues as well.
Brad

 

Did you recently change your Trans fluid and filter? When I did mine I accidentally broke the tcc solenoid I think it was call and didnt notice, only had gears 1 and 3 til I took it apart and noticed what I did