Two problems related to power steering pump have been reported for the 1997 GMC Yukon. The most recently reported issues are listed below.
The first time the power steering unit went into a hyper-super-squirrely(only mometary) mode was at 5000 mi. Vehicle has been to the dealership several times with the same response from the dealership every time, could not duplicate problem. The evo sensor has been replaced but the problem manifested once again after a few hundred miles. Steering has gone "hyper" at speeds above 30 mph, turning left and right, as well as on straight sections of roadway. It is a very frightening feeling to lose control of several thousand pounds of steel traveling at freeway speeds. Luckily I have always managed to regain control before going off of the road, I hope my luck continues. I suspect GMC will not remedy this situation unless numerous people are killed first.
Power steering assembly leaked. Certified mechanics have replaced assembly 4 times now. It is thought that the seal area between the pump assembly and fluid resevoir was warped. Resevoir replace this last visit. Am really interested in knowing if this problme has been common to Yukons.