transmission not shifting on 1992 Volvo 940

what happens if i continue to drive the car with the transmission not shifting at 60 mph?

Asked by for the 1992 Volvo 940
what gear is it in, and what are the rpm's when you are going 60?
it is drive and the rpm's are 3 to 3.5
If it isn't the kick down cable, could a bad solenoid be the problem? how much would it cost to replace a solenoid? what other potential problems could it be?
1 more answer
It maybe you the over drive relay that is the culprit. They run about $30-50.