ECM/FICM Harness Resistance
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Turn ignition switch to LOCK position. Disconnect ECM/FICM and appropriate component harness connectors. Check for open or short circuits between appropriate ECM/FICM harness connector terminal and appropriate component harness connector terminal. If harness is open or shorted, repair as necessary.