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 system voltage must be between 9.0 and 16.0 volts.
The ignition switch must be in the RUN position.
The park brake must be released.
The headlamp switch must be in the AUTO position.