99 Explorer XLT V-8

In the sense that ABS is a safety device... yeah, it can be urgent.....

In the sense that is the truck going to crash because of it.... probably not (unless the red brake warning indicator is on, as well... which is also providing that the red warning bulb works).

As long as there are no unmentioned concerns with the base brake system, the major side effect will be no ABS activation if needed.

For my dime, warning lights are things I don't disregard... especially when anything related to my safety or the safety of my family and/or passengers is concerned. Not passing judgement here but not one person that died or was seriously injured in a traffic mishap set out with the idea that "THEY" were the ones the reast of us read about....