Pardon my mistake, the central triangle warning light is orange, not red, indicating a non-urgent fault.
I discovered that with the door closed and the engine running, by holding down the READ button on the end of the left stalk along with the trip meter button for ten seconds I get a beep and then a code. The code is just 44, nothing else. I have the VADIS but cannot find anything in there about code 44.
I googled volvo s80 code 44 message center and got a hit from this website, someone had this code and said it was related to the cruise control. He changed the brake diaphragm position sensor and it was fixed. I can't find anything in VADIS about cruise control, but I did find the brake pedal position sensor. Its in the engine bay on the brake booster. I never use cruise control but I'll try that first.
If anyone knows anything more about code 44 please let me know. One would think there would be a list of codes published somewhere. Thanks.