Diagnostic Aids

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

APP sensor 1 and APP sensor 3, 5-volt reference circuits are internally connected within the ECM.
The APP sensor 2, 5-volt reference circuit is shared with the Barometric (BARO) pressure sensor and the turbo boost solenoid and they are internally connected within the ECM.
If the problem is intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.