I drive a 2005 GMC Yukon 4x4. I recently noticed my yellow brake warning light coming on. I jacked up the front of the truck, thinking I’d take a look at the brake linings. Just before removing the wheels I noticed the right front wheel was loose when I grabbed it and shook it compared to the left one. It moved in and out by a half-inch about where my hands were. I checked the lug nuts and they are tight. Where do I proceed from here? I parked it in the mean time.
Your message shot right to the top of my want-to-help-with list, as this is a dangerous situation. Based on the two symptoms you mentioned, it sounds like the Yukon’s right front hub (wheel) bearing is beginning to come apart. Should a hub or wheel bearing become loose enough, it will often cause the ABS brake system wheel speed sensor, located within the bearing hub on the Yukon, to rub against the reluctor, the toothed surface of the hub. That can damage it, resulting in an illuminated warning light and diagnostic trouble code being set.
The good news is that modern wheel bearings are often consolidated into a bolt-on hub assembly, making replacement pretty simple. But the bad news is the parts cost is downright ugly. What used to be $25 to $50 in parts and grease for individual bearings can reach $400 or so for the bolt-on hub assembly.
If you’re a do-it-yourselfer, this job is pretty straightforward after removing the wheel, brake rotor, caliper, and caliper bracket. The only tough part is some very tight and large metric bolts (21 and 22mm, and axle nut (36mm), which require tools that are likely beyond the scope of the typical home tool box. The axle nut should also be renewed, as its self-locking capability cannot be trusted after removal and reinstallation. It’s tightened to 177 pound-feet.