Conditions for Setting the DTC

WARNING: This page is about a different car, the 2003 Buick Regal and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.

The BCM detects that the DRL ambient light sensor signal circuit is greater than 4 volts or is open when it is trying to enable the automatic autolamp control feature.
The DRL ambient light sensor signal circuit is open or shorted to battery positive voltage.
The DRL ambient light sensor low reference circuit is open or shorted to battery positive voltage.
The ambient light sensor is open internally.
The condition above must be present for more than 0.3 seconds.