Code 74, Transmission Input Speed Error 4L80-E Transmission: Notes

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 1995 GMC Vandura, 1995 GMC Rally, 1995 GMC Pickup, 1995 Chevrolet Sportvan, and 1995 Chevrolet Pickup. However, it is still accessible from the selected car via links, so may be relevant.

Sensor is a permanent magnet type. When rotating trigger teeth pass sensor, an AC voltage signal is produced. Signal voltage and frequency varies with forward rotational speed.

NOTE: Test numbers refer to numbers on diagnostic chart.

Checks entire circuit for continuity.
Checks output of input speed sensor.