POWER STEERING PUMP FAILURE 2001 YUKON XL. DEALER DETERMINED FAILURE TO BE A SHEARED SHAFT ON THE POWER STEERING PUMP, WHICH CAUSED IMMEDIATE LOSS OF POWER STEERING. FORTUNATELY THE FAILURE OCCURRED AT LOW SPEED IN A PARKING LOT. DEALER AND GM CONCLUDE THAT FAILURE WAS DUE TO COLD WEATHER . TEMPERATURE (ACCORDING TO LOG FROM LOCAL AIRPORT) WAS 21.2 DEGREES F AT THE APPROXIMATE TIME OF FAILURE (ABOUT 5:30 PM ON 2-5-2004). VEHICLE MILEAGE WAS APPROXIMATELY 46,000 MILES AT THE TIME. THE LOSS OF POWER STEERING WAS IMMEDIATE TURNED ONE DIRECTION, EVERYTHING WAS FINE, TURNED BACK AND HAD NO POWER ASSIST. ATTEMPTED TO REMEDY THROUGH GM AND WAS FLATLY DENIED, ALTHOUGH DEALER SERVICE MANAGER ADMITS THAT THIS IS NOT A RARE OCCURRENCE ON VEHICLES OF THIS PLATFORM. I AM PERSONALLY AWARE OF ONE OTHER FAILURE ON SIMILAR VEHICLE (CHEVY PICKUP), WHICH WAS COVERED UNDER THE STANDARD 36,000 MILE WARRANTY. GM APPARENTLY DOES NOT CONSIDER THIS IMMEDIATE LOSS OF POWER STEERING ON A 5500 POUND SUV A SAFETY ISSUE I ON THE OTHER HAND AM JUST GLAD IT DID NOT OCCUR AT HIGHWAY SPEEDS.*AK