DTC will test when the following conditions are present:

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.

No TP sensor DTCs are set.
No ECT sensor DTCs are set.
Engine coolant temperature is greater than 162°F (72°C).
Intake air temperature is greater than -13°F (-25°C).
BARO is greater than 70 kPa (less than 10,300 ft.).
VSS is less than 2 MPH.
No VSS DTCs are set.
No MAP sensor DTCs are set.
System voltage is greater than 10 volts but less than 18 volts.
Engine run time is greater than 30 seconds.
Throttle position is less than one percent.
All conditions are met for greater than 3 seconds.