Transmission problem

[512Dave]

My 2010 Silverado will not shift out of first gear. It shows a P0121 code for “Throttle /Position Sensor/Switch A Circuit Range/Performance” Any help greatly appreciated. 

[CamGTP]

Any other codes?

 

The top left corner shows that there are 7 codes?? Because that is 1 of 7.

 

Typically range/circuit codes are wiring related and sometimes the sensor itself. Having a scan tool that can do live data is helpful so you could do the tests if you had a GM service manual to know what the specs are.