Diagnostic Aids
WARNING: This page is about a different car, the 2011 GMC Yukon, 2011 Chevrolet Tahoe, and 2011 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
The 42 volt circuit is only used by the electronic power steering. The accessory DC power control module can apply 42 volts on the connector without being connected to the electronic power steering.