| Subject: | Service 4WD Light on, Transfer Case Inoperative Possible Water Contamination |
| Models: | 2007-2008 Chevrolet Silverado |
| 2008 Chevrolet Avalanche, Suburban, Tahoe |
| Equipped with NQF or NQH Transfer Case |
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Some customers may comment that the service 4WD light is on and that the transfer case is inoperative. The dealer technician may discover multiple DTC's currently set or in history.
Recommendation/Instructions:
The concern may be caused by water contamination in the connector at the transfer case actuator (encoder motor). As a part of the standard strategy based diagnosis the dealer technician needs to check the integrity of this connection. It is possible
that water is leaking past the weather pack seals and into the connector. If this is happening the resulting corrosion will appear on the affected terminal. All corroded terminals and weather packs will have to be replaced. The actuator may also have to be
replaced if the pins are corroded.
After the terminal repair the dtc's should be cleared and the system retested to see of the dtc's reappear, if any dtc's reset please follow the appropriate dtc flow chart.
Please follow this diagnostic or repair 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.
