Conditions for Setting the DTC

WARNING: This page is about a different car, the 2005 Buick LaCrosse and 2005 Buick Allure. 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, 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 battery positive voltage or open.