Conditions for Setting 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.
There is a short to ground in the Interior park lamps fused supply voltage circuit or an open in the park lamp relay control circuit.
If the Interior park lamp fused supply voltage circuit is open, regardless of the headlamp and panel dimmer switch position, the DTC will set.
If the park lamp relay control circuit is open, with the headlamp and panel dimmer switch in the AUTO mode, the DTC will set.
The system voltage must be between 9 and 16 volts.
The above conditions must be met for 0.5 seconds.