Circuit Description
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 1997 GMC Yukon, 1997 GMC Suburban, 1997 GMC Pickup, 1997 GMC Cab & Chassis, and 1997 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
While engine is warming, VCM monitors ECT sensor to determine the amount of time it takes engine to reach coolant temperature required for closed loop operation. Test will not be run if either intake air or engine coolant temperature are less than predetermined temperature. VCM will only run test on a cold start and only once per cold start.