DTC 68, Transmission Component Slipping (4L80-E): Notes

PCM monitors difference in engine speed and input speed. With transmission in Drive and TCC locked, scan tester should display engine speed closely matching input speed. DTC 68 will set when:

DTCs 28, 71 or 74 are not set.
TCC slip speed greater than 200 RPM.
4th gear is indicated.
TCC is locked.
Not in Park/Neutral.
All conditions are met for 2 seconds.

PCM will default to inhibit TCC operation.

NOTE: Test numbers refer to numbers on diagnostic chart.

This test checks the indicated range signal to actual selected range. A faulty switch could set DTC 68.
This test checks torque converter for slippage while in commanded lock-up state.