2005 Chevy Silverado service 4 wheel drive message

here is some info,check the following.Some customers may comment on intermittent illumination of the Service 4WD light. Upon investigation, the technician may find DTC C0374 set. The customer may also comment on intermittent erratic operation of the 4WD or AWD system after driving through rain/snow or simply going through a car wash.

Cause
The speed sensor signal may have become corrupted. Possible openings in the speed sensor wire insulation (twisted pairs) can allow water intrusion. Also, wire connections contaminated by water may result in short circuits and erroneous speed sensor readings. This most often occurs on the rear speed sensor circuit.Inspect the wiring harness to the transfer case speed sensors. On Rainier, TrailBlazer, Envoy and 9-7X models, fabricate a replacement speed sensor harness between the C101 connector and the speed sensors. Replace the affected twisted pairs. Do not over-twist the two wires in the replacement harness. Wires should be twisted at a rate of 9 revolutions per foot.The smaller transfer case harness splices into the larger chassis harness a few inches in front of the crossmember. The chassis harness routes along the left side of the frame under the driver door area. Use nylon tie straps to secure the fabricated harness to the main chassis harness between the transfer case and C101.On the full-size pickup and full-size utility models, replace the 2.2 m (88 in) pigtail harness that runs from the C151 connector under the hood to the transfer case. I know this info says rain,snow or a car wash but check it anyways could have corrosion.also autozone does not always have the wright equipment,there probably is a code there equipment will not identify t-case codes.here is a place to start,post back with what you find.