2006 F-53. Doing brake overhaul found rear rotors did NOT have ABS rings in them. Both hubs have ABS sensors, this is a 4 channel system. I had no ABS light on. Stupid me went and replaced the rot...
Your ABS sensors all have an electrical plug about 2' away. Take your ohmmeter and check the resistance of each sensor. ON my coach they all read about 1200 ohms. If all of your sensors have the same reading, then I would suspect that your missing ABS rings MIGHT be the problem, assuming that the main ABS module is working properly. MY ABS sensors all read about 1200 ohms. Your's may have a different reading. What you are looking for is for all of them to read very close to the same.