We drove our Blazer yesterday. We pulled into a parking space at a store and when we got ready to leave we had no reverse. We added fluid which helped the shifting in forward but no reverse. Can anyone tell me how to troubleshoot. We are senior citizens but we still try to do most of our own repairs but we do not know anything about automatic transmissions.

 

Do you have all 4 forward gears? If not, the reaction sun shell has failed which can happen in these transmissions without warning. If this happens, the transmission will be left with only 1st & 3rd gears.