With 4L60 Transmission

Circuit Description
The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to the throttle opening. Signal voltage will vary from about 0.5 volt (0%) at idle to about 5 volts (100%) at wide open throttle.
Code 22 means that the ECM has seen the following:
^ Low voltage at ECM terminal "A2".
^ For a time in excess of2 minutes.
^ Engine speed greater than 1250 rpm.

Test Description
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Confirms Code 22 and that fault is present.
2. Simulates Code 21, (high voltage). If the ECM recognizes the high signal voltage, the ECM and wiring are OK. If signal voltage is still low, Code 23 will set, because the test was performed below 1250 rpm.