Conditions for Setting the DTC

WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

A DTC B1428 sets when the BCM detects a short to ground in the ignition 1 voltage circuit of the relay when the output is controlled active.
A DTC B1428 sets when the BCM detects an open in the ignition 1 voltage circuit of the relay when the output is inactive.
The conditions above must be present for more than 0.3 second.