In the winter when there was lots of snow it would throw both an ABS light and brake light and it would go away when dry. It went away as soon as it got warmer but the the last few days of rain it tends to pull real hard to the right and takes dang near forever to stop.

I had the brakes checked a month ago after it had an issue in the rain and the mechanic could find nothing, all rotors and pads in good condition.

What would make the van want to pull right and take a long time to stop but only in really wet conditions. It hasn't thrown a light in the rains yet.

Bad tires.

I have changed plenty of stuck calipers on those vans. Just changed a pair last week. They can act very odd at times, not what you would normally think and not be consistent.

(1) the dr side ain't doing its job (for whatever reason) (2) water splash is getting up in there to the caliper surface (somehow).

Sounds like water is the culprit like going thru a puddle, but the pads and rotors should disperse that..the problem seems to be in the drivers side not working and the abs sees that and sets the light on..you can verify that when you check the codes