Circuit Description
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The engine control module (ECM) enables the appropriate fuel injector on the compression stroke for each cylinder. The ECM controls the fuel injection control module (FICM) by grounding the control circuit via a solid state device called a driver. The ECM monitors the state of the driver. If the ECM detects an incorrect voltage for the commanded state of an injector driver, DTCs P1223, P1226, P1229, P1232, P1235, P1238, P1241, or P1244 will set.