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 EVAP DTCs are set.
No IAT sensor DTCs are set.
No MAP sensor DTCs are set.
No ECT sensor DTCs are set.
No MAF sensor DTCs are set.
No intrusive test is in progress.
No device controls are active.
System voltage is at least 9 volts.
Engine run time is greater than 2 minutes.