The same reservoir that serves front wipers serves the rear window. If the rear sprayhead is not working then it may be blocked or the line to the engine compartment may be pinched, or have come disconnected.
Front reservoir also serves the rear
The washer pump is on the bottom of the fluid reservoir.
the same reservoir as front
No, the rear fluid comes out of the front reservoir.
The 2004 GMC Yukon has 16 valves.
The 2004 GMC Yukon has a V8 engine.
line might be plugged or pump is burned out
The 2004 GMC Yukon has overhead valves (OHV).
The 2004 GMC Yukon has a 4-speed automatic.
The 2004 GMC Yukon is a gas-powered vehicle.
Both sets of window washers are fed from the same reservoir under the hood.
My 2003 4 runner window also does weird things. I found that over time the window actually settles down ( most likely from opening and closing the rear hatch. ) so now when it gives me weird problems I open it and re-close it. This resets the safety switch. (it keeps your window washer and wiper from working if the window is open. ) The window may look closed but in truth it's settled just enough to make the switch think it's open. I had the same problem (rear washer/wiper didn't work. I first checked the fuse and when it turned out to be OK I came here. The above answer fixed the problem. Thanks!!