DTCS 21/22, TP Sensor Circuit High/Low (4L80-E With TCM): Notes

TP sensor contains a resistor strip with one end connected to a 5-volt supply and other to ground. Signal circuit is connected to a movable contact within TP sensor. As accelerator pedal is applied, voltage signal will increase from about .5 volt to 4.5 volts. DTC 21 will set when:

Engine operating.
TP sensor signal voltage greater than 4.9 volts.
Conditions met for one second.

DTC 22 will set when:

Engine operating.
TP sensor signal voltage less than .2 volts.
Conditions met for one second.

TCM will default to maximum line pressure, use 35 percent throttle as default, and inhibit 4th gear if in hot mode.

NOTE: Test numbers refer to numbers on diagnostic chart.

This test checks for presence of 5 volts at TP sensor.
Scan tester should display 5-volt reference to TCM.