Just FYI and thanks to the forum! I bought the Steering Motion Sensor for my 99 Yukon at O'Reillys for $33.00. I believe it is made by Dorman. The steering on my kon was sloppy and loose, basically the power steering was giving full boost because of the faulty sensor. Anyway, the part is located on the steering column under the front dash. It is donut shaped with a pigtail connector. Google the part and click on shopping and you'll see plenty of pictures/prices for it. The great thing is after replacing it (15 minute process) the Yukon drives like new now. The old sensor was dirty and corroded, the power steering is now adjusting the fluid pressure as it should. The process to r/r is easy. Using a 15 mm wrench remove the carraige bolt that is right below the sensor, then push the column down toward the floor to open a gap in the column. The donut sensor is held into a plastic retainer with three clips, I was able to pry them apart with my fingers and wiggle the sensor out. Disconnect the electrical connection (6 inches from the donut), then slide the sensor down and off the column. Pay attention on which side is facing up as you remove it. Slide the new one up the column and snap it into the retainer (pigtail is facing up and fits into a notch at the twelve o'clock position). Reconnect the electrical plug. Pull the steering column back up and into the columns housing, slide the carraige bolt back in and tighten the bolt. One tip is to have your wheel turned to the left a little so then you can use a socket wrench to tighten it back up. Also, you will notice that the inner section of the sensor rotates and that there is a U shaped depression at the top. I lined that up with the pigtail and with the wheel straight as I slid it back up into the retainer. Then I reconnected the column, slipped the bolt back in, then turned the wheel to the left in order to use a 15mm socket on the nut. Bottom-line: If your steering is loose with a constant feeling of less control, then replace the sensor. It will be the best $33.00 and 15 minutes you have ever spent on your SUV. Thanks to the forum for all the guidance in other posts.
Al