Circuit Description
WARNING: This page is about a different car, the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 Chevrolet Tahoe, 2002 Chevrolet Suburban, and 2002 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
The 4WD LO Circuit is used to notify the powertrain control module (PCM) that the vehicle is in 4WD low range. The PCM supplies 12 V to this circuit. The transfer case shift control module grounds this circuit when the vehicle is in 4WD low range.
This DTC detects an transfer case shift control module problem, a short to voltage on the 4WD LO Circuit.