Circuit Description
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Suburban, and 2003 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
When the ignition is turned on, the PCM will turn on the in-tank fuel pump. The in-tank fuel pump will remain on as long as the engine is cranking or running and PCM is receiving reference pulses. If there are no reference pulses, PCM will turn the in-tank fuel pump off 2 seconds after ignition is turned on or 2 seconds after engine stops running.