2004 V70 ABS/STC issues

[Ulyssesm90]

Hey y'all!
Car newb here. I did as much research as I could on my own but I thought I'd post my specific problem to the awesome people on this forum anyway as I need as much help as I can. About a week ago the STC light started coming on and unusual amount and enganging only at very, very low speeds (turning out of the driveway, etc.). Soon enough I got the dreaded "ABS/Anti-skid" service required error message and what's happening now is again only at pretty low speeds the STC is engaging when it just doesn't need to, and I'm hearing what I believe is the ABS pump clicking pretty loud, which I've only ever heard before when I actually needed this feature during say inclement weather and was skidding a bit. The light has been going on and off and the sound is engaging pretty significally even occasionally when just driving straight down a road, but again only at a low, near idling or under 10-mph speed. When I speed up to a reasonable speed the problem resolves. The brakes feel fine, I haven't gone under the hood yet (mostly because I'm trying to figure out what to look for first). Does this sound like I just need to rebuild ABS unit like a lot of other Volvo owners seem to need to do? Does it sound like something else? Obviously as a car newb I worry not only about worst-case scenarios involving brakes failing or something but also about the cost of replacing the entire unit if necessary, plus mechanic costs. For now when it's been acting up particularly bad I've just been turning STC off and that too resolves the problem, and I can get away with that now because it's the summer months and I'm doing any particularly crazy driving, but as a New Englander I want to get this resolved before winter hits.

Any help and advice would be deeply appreciated. You guys rock!

[DGM]

I fixed a similar issue last year on a V70 2005. It was a defective ABS tone ring. You may want to investigate. I used Dorman 917-553 on both sides to replace. The ring is affected by corrosion and split.

I found this image to indicate what to look for;