It is normally off but it has weird behavior after clearing codes. I've experienced clearing codes and then the ABS light still not going out till you drive a few MPH then it goes out. I recall having to play with it after fixing a dirty wheel speed sensor and it wasn't straightforward how to get the light to turn off. But it did sort itself out.
I did recently do some ABS light troubleshooting on an A1P2 and that truck (2021 model built by Oshkosh - 06/21
) turned out to have a poor ground from the chassis to the cab - they hadn't cleaned off the paint on the cab mount for the ground strap and it had about a 1.5v - 3v drop between the cab and the chassis. The ABS computer was running but was throwing a circuit code for the retarder relay control. That resolved on it's own once the ground was fixed.