Volvo: 1994 volvo 940 stuck in overdrive, volvo 940, current relay

Question
Answer -
If you're confident the overdrive button on the shifter is ok, I would guess you have a fautly overdrive relay, which is very commond in these cars.  You can test and clean your current relay or get one from a junk yard to test for a few bucks, or just have it replaced with a new one.  Good luck!

Can you provide an idea as to where the overdrive relay is at?

Answer
Because I only have experience with the 240 series, I can't tell you for sure, but for me it was located behind and to the left of the glove box.  To get a more accurate answer, consult a Hayne's manual, or post this question at www.brickboard.com in the 900 series section, so those who own the same model can give more specific information.  Good luck!