My 2004 XC90 2.5T AWD celebrated 195K miles by giving me the "ABS Service Required" message. It was clear that AWD was not working due to wheelspin, but ABS was working due to several (unintended) highway offramp experiments on the DC beltway.
I remembered visiting SIS in Rockville from the Volvo meet there several years ago, and happened to notice they were on Xemodex's go-to list. Took a bit of drive from N. VA in July, they diagnosed it was the DEM at fault, notably not the BCM/ABS module. Booked a return date (after summer's end) in Sep, gave up the car for a period of time, had the module removed & shipped to Xemodex, then returned to & reinstalled by SIS. I had a long talk with the tech under the lift, I was very impressed with him and the shop overall.
(I also had the TCM tested due to a one-off message, but they found no problems and returned that module at no additional cost beyond a bump in shipping expense. Fingers crossed it was a fluke related to DEM issue.)
Car is now driving very well, no issues now and hopefully no more to come for a long time. I've had several encounters with repairs to Volvo electronics (CEM, ETB, now DEM), I'm kind of over this part of the Volvo ownership experience. But this was a reasonably cost-effective solution for an older, high-mileage car that's not worth much more than my emotional attachment to it (which wife neither understands nor approves of).
The only complication throughout the entire process was shipping quote/paperwork/customs -- I lost multiple, extra days due to slow iterations of shipping info coming from Xemodex to SIS, plus a customs delay going to Canada due to an error/omission in paperwork. Your service tech may be inexperienced dealing with this process, make sure they stalk Xemodex so that everyone is clear on how this works and your module doesn't get stuck in mail purgatory. But so far, the technical solution is solid and I'd use both providers again if yet another electronics problem comes up.