Conditions for Setting the DTC: P1831
WARNING: This page is about a different car, the 2009 Pontiac Torrent and 2009 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
The TCM detects an internal open or short to ground in the high side driver 1 for 0.3 second or greater of a 0.5 second sample.