Chevrolets May Have Missing Connector Seals
This bulletin applies to 2015-2019 Chevy Tahoe and Suburban, 2015-2018 Silverado, 2019 Silverado LD and Silverado 2500/3500, and 2015-2019 Colorado vehicles equipped with 4WD. An intermittent service 4 wheel drive message may be displayed in the instrument cluster.
The cause may be wiring terminal issues resulting from a missing seal around the wires. When diagnosing intermittent transfer case control module DTCs related to signal or circuit integrity including C0321, C0392, C0396, C0398, C0306, C039E or C038D, inspect the related connectors and ensure that the seals are properly installed in the connectors. Missing seals allow moisture inside the connector and will cause repeated conditions and/or different intermittent conditions.
Some connectors are serviced as a connector. Some have terminal leads and some are available as a harness only. If there is corrosion in the connector and needs to be replaced, the mating side of the connector should also be replaced, whether it is another connector or an electrical component.