How do you extract 1990 Volvo 760 Turbo Wagon Engine Codes?

My indestructable 1990 760 Turbo Wagon just started running like crap today, it would idle poorly then die with any load on the engine. I found a few suspect vacuum lines, especially the one to the fuel pressure regulator, and after replacing them it seems to be running better and is driveable, but not great. And now the check engine light is on. How do you read the codes ?? Is there a magic incantation that will cause the codes to blink out somewhere ?
How do you extract 1990 Volvo 760 Turbo Wagon Engine Codes?
look for it gosh! pick my answer pleeeeeeeeeeeeease!
How do you extract 1990 Volvo 760 Turbo Wagon Engine Codes?
you have to have a scan tool they are pretty spendy and you most likly dont have one you will have to take it to a shop and have them run the codes, but done get to worked up if the check engine light is not flashing its not a big worry when its on steady its just an emmsions code