96 GMC Yukon ABS light is always on

If there is nothing obvious, there is one strange thing that can cause this on these vehicles. Check the operation of the high centre mount brake lamp. It is a row of LEDs. If even one is not working, your ABS light will illuminate.

That is odd Michael, my "thing I learned today" Good information.I bet it would not throw a code on an OBDII scan, which your Yukon has, The Federal law states "All light duty vehicles beginning with Model Year 1996 are required to have an Onboard Diagnostic Port located within three feet of the driver and require no tools to access"....then the statute goes on about Heavy Duty and so on..but that does not mean it's in plain sight, could be behind ashtray, cupholder, etc. and even if your Yukon or any car was built and sold in 1995, if labeled by manufacturer as 1996 Model year it has to have OBDII. No more counting flashes and patterns of CEL. OK I went on a tangent what I was getting at the mechanic might not know that about the third brake light, no code displayed and is stumped because of that.

could be a bad wire or abs cable going to the sensor on the bearing assembely or sould be a bad sensor , may have to look to see which ones bad or change them out to find the right one thats bad , is the brake light on also ?

Jim: The reason for the cruise being disabled when the 3rd brakelight is out is very simple: That light coming on is what trips the cruise into coast mode when you tap the brakes. As a safety feature, when the lamp does not work, the cruise will not engage, otherwise tapping the brakes would not disengage cruise, which is as scary as HELL!