Conditions for Setting the DTC

WARNING: This page is about a different car, the 2004 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

When the BCM receives a instrument panel controls illumination lamp request signal and the instrument panel dimming reference circuit is shorted to ground, open or short to battery positive voltage.
When the BCM is not receiving a instrument panel controls illumination lamp request signal and the instrument panel lamps dimming signal circuit is shorted to voltage or open.