my 2002 s 10 sudenly start not shifting it feels like is staying in 3th gear I would like to know what to change because , I dont want to be replacing every thing if someone give me an opinion I WILL BE GLAD thenkyou.

 

It sounds like your transmission is in Limp Mode. This is usually caused by either a bad Control Unit, a bad shift solenoid, a bad pulse generator, or a bad TPS. One way you can test the control unit is to open it up and check for popped capacitors. This is the number one cause for Limp Mode. A popped cap is going to be swollen on the top or leaking a yellowish fluid. If all checks out on the control unit, you probably have a bad sensor. I would start with the pulse generators first. They read the input and output shaft speed. If they don't match up with the programmed settings, the transmission thinks it is slipping too much and kicks into limp mode.