I've attached a PDF of typical plumbing systems. They have evolved over the last few years. The as-shown system is how they were for many years, with a screw-in hose connections for city water and a flip open funnel-like connection for the fresh water tank fill. Then they added a screw-in connection for the anti-freeze fill line. In this case, you had a valve in each feed line to the pump, one in the antifreeze line and one in the FW tank line. Using these, you could actually fill the FW tank with the city water hose attached to the antifreeze fill connection. However, in the upper left is the next evolution (brown ovals), which was to eliminate the two suction valves and replace them with a 3-way valve. This typically prevents you from filling the FW tank from the antifreeze connection. The 2nd evolution is shown in the lower right (purple ovals). They've added another 3-way valve in the city water line that goes to the FW tank and they've eliminated the flip open FW tank fill. Some people are concerned that someone will pour something nasty down the flip-open fill, so this arrangement eliminates that concern. This arrangement seems to be prevalent on new 5'vers, based on my forum browsing, anyway. Your plumbing may be any combination of these arrangements.
Also pay attention to the 3 valves at the water heater. Many folks forget to close the bypass valve. This causes them to get about a minutes worth of hot water, then it turns cold.
Hopes this helps.
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2011 Traverse LT, 3.6L, FWD
2009 Silverado Ext Cab, 5.3L, 4x4, 3.73
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