Diagnostic Aids
WARNING: This page is about a different car, the 2012 GMC Yukon XL, 2012 GMC Yukon, 2012 Chevrolet Tahoe, and 2012 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
If the 5-volt reference or the switch signal wire are shorted to ground the scan tool can show up to 7.5 volts.