Conditions For Running DTC

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.

DTCs P0461, P0462, P0463, P2066, P2067, or P2068 are not set.
The engine is not running.
The vehicle speed is 0 MPH.
The primary fuel level is less than 6.6 gal. (25 L).
The secondary fuel level is more than 0.7-2.6 gal. (3-10 L).
The above conditions are met for 20 seconds before the secondary pump is commanded ON.
The secondary fuel pump is commanded ON for 120 seconds.