The engine system service required message has been haunting me for a while. I have a Tech force OTC scanner but could not find what the problem was, so I called a friend that has a volvo scanner. I was shocked to find over 25 soft codes and 1 hard code stored that I couldn't see with mine. I did not have a check engine light. The hard code was 9400, the brake pedal position sensor. after replacing it I am now message freeand the cruise control works.

The point is obvious to me now. The only way to see the full picture of what is going wrong on these vehicles is with a volvo scanner. I hope this saves you some time and frustration in the future.