Important Information

Subject: 2004-2005 Full Sized Trucks and Utilities Transfer Case Control Module Contaminated by Water Intrusion - keywords NP8 246EAU B0790 C0300 C0305 C0306 C0321 C0321 C0327 C0359 C0374 C0379 C0550 4WD PIP3352 - (03/04/2005)

Models: (2004-2005 Chevrolet Silverado) and (2004-2005 Chevrolet Suburban) and (2004-2005 Chevrolet Tahoe) and (2004-2005 Chevrolet Avalanche) and (2004-2005 GMC Sierra) and (2004-2005 GMC Yukon) and (2004-2005 GMC Yukon XL)

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described.

Condition/Concern:
Service 4WD light on with either a variety of DTCs or no communication with the transfer case control module.

Recommendation/Instructions:
Inspection of the transfer case control module (TCCM) may reveal the connector to have evidence of water intrusion. The most likely cause of this water intrusion is a leak from the windshield to body seal.

Repair the water leak as necessary.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.