Conditions for Running the DTC

WARNING: This page is about a different car, the 2002 GMC Safari and 2002 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.

The key is in the RUN position.
The park brake is released.
The headlamp and panel dimmer switch is in the AUTO mode.
The ambient light sensor is in the DARK state.
The system voltage must be between 9 and 16 volts.