ABS light popped on - looking for probable reasons

My ABS warning light popped on for the first time ever a couple of days ago when I started up my truck. I also noticed that I couldn't shift into DRIVE. I restarted and the light did not reappear and I could shift as usual. Note of concern at that point. Yesterday I drove it about 5 minutes without issue THEN the ABS light popped on again for about 15 seconds and then went off. Higher level of concern now. I'm wondering what may be the likely reason for these events.
I welcome thoughts from those who have had this experience obviously and those who are familiar with this issue.
Thanks

 

Did you have any work done recently where a wheel speed sensor could have been damaged?

 

Check the brake switch down on the brake pedal.

 

My abs light was kinda doing the same thing.
My truck is manual so no shifting issues.
I was just a little low on fluid and it was triggering my light. Found that here thanks TW! Sounds like the switch if it would not shift though. But I don't think the switch would trigger the abs light?

 

This might help:
https://www.tacomaworld.com/threads/2007-taco-abs-brake-light-on-no-reason.75649/