DTC 22

Circuit Description:
The Throttle Position Sensor (TPS) is a variable resistor that signals the ECM the degree of throttle opening. The sensor is connected to a 5 volt reference and has the highest resistance at closed throttle. At wide open throttle, the resistance is lowest and output to the ECM will be near 5 volts.
Code 22 means that the ECM has seen the following:
^ Low voltage at ECM terminal "A2".
^ For a time in excess of 2 minutes.
^ Engine speed greater than 1250 rpm.

Test Step Description:
Numbers below refer to the circled numbers 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.