Circuit/System Description
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2011 GMC Yukon XL, 2011 GMC Yukon, 2011 Chevrolet Tahoe, 2011 Chevrolet Suburban, and 2011 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
The control module enables the secondary fuel pump relay when the ignition switch is turned ON. The control module will disable the secondary fuel pump relay within 2 seconds unless the control module detects ignition reference pulses. The control module continues to enable the secondary fuel pump relay as long as ignition reference pulses are detected. The control module disables the secondary fuel pump relay within 2 seconds if ignition reference pulses cease to be detected and the ignition remains ON.