Circuit Description

WARNING: This page is about a different car, the 1997 GMC Pickup and 1997 Chevrolet Pickup. 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.

DTC will set when the following conditions are present:

Engine running.
ECT is greater than 15°F (-9°C).
IAT is greater than 19°F (-7°C).
Vehicle speed is greater than one MPH.
Start-up ECT is less than 104°F (40°C).
Closed-loop timer greater than 4 minutes.
Minimum stabilized ECT is less than 68°F (20°C).