Conditions For Setting DTC

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 1998 GMC Yukon, 1998 GMC Suburban, 1998 GMC Pickup, 1998 GMC Cab & Chassis, and 1998 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.

System will set DTC when the following conditions are recognized:

Critical operational parameters stored in EEPROM have failed checksum test, indicating invalid data.
Masked ROM code has failed checksum test, indicating masked ROM data is no longer valid.
ROM code has failed checksum test, indicating ROM data is no longer valid.
One or more RAM locations have failed operational test, indicating some portions of RAM are not functional.
Motor circuit test has indicated one of the control module relays is not able to make contact.

When this DTC occurs, SERVICE 4WD light will be on and system will be disabled. To repair this DTC, replace ATC control module, then perform ATC SYSTEM CHECK .