Diagnostic Aids
WARNING: This page is about a different car, the 2009 GMC Yukon, 2009 Chevrolet Tahoe, 2009 Chevrolet Suburban, and 2009 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.