WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
Ignition 1 Signal - ECM
Circuit
Short to Ground
Open
Short to Voltage
Operating Conditions:
Ignition ON, engine OFF. Parameter Normal Value:
12.6 Volts