Diagnostic Aids
WARNING: This page is about a different car, the 2009 Pontiac Torrent and 2009 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
Test the current out-put of the 5-volt reference circuits if you suspect high resistance in the circuit. The current out-put should be greater than 80 mA for APP 1 and greater than 50 mA for APP 2.