Q: I have 2000 silverado. i came to a stop and all of a sudden the trans wont up shift from 1st gear

A scan tool can be used to see if the shifts (1-2, etc.) are being commanded. If you find they are being commanded, that is an indication that the "computer" part is working and so you would look at possibilities such as: 1) TCC lock solenoid/wiring harness defective; 1-2 shift valve is sticking; valve body faults (warped, leaking, etc.); defective 2-4 Servo Assembly; worn 2-4 Band Assembly or band anchor pin is not engaged; defective throttle position sensor. There are other causes as well. The only way to diagnose this or any like issue is to have the 4L60E manual in hand because you have to start at the top of the diagnostic tree and work your way down. A diagnostic is available from YourMechanic; please simply request a shift diagnostic and the responding certified mechanic will identify the fault. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.