ABs light was on intermittently, now on steady

[bobbo]

'08 Lucerne ABS light was on and off periodically for months. Now it is on steady. I checked each wheel with a voltmeter and got a reading when I spun the wheel. I want to check continuity from each wheel to the ABS controller, and check for anything else that would be causing this problem. Anyone have a wiring diagram, trouble shooting information, etc.? Any help is appreciated. Thanks!

 

[2007LucerneCXL]

A scanner would be the best option to consider as it would identify which hub is the suspect.