Volvo Repair: 1992 240gl cant engage 4th speed, speed light, glove box

Question
hi there,
after starting our volvo the disengage 4th speed light on the dashboard came
on, and indeed it is not shifting into 4th gear anymore. it was fine when i
parked it a couple of hours before. pushing the button doesn't work.the light
stays on, even after restarting the car.
any tips on how to fix this or how much it might be to get it fixed would be
greatly appreciated.
thanks

Answer
Stephan, check the fuse first.  Even though it may look okay, remove it and check.  It that doesnt help then its the relay behind the glove box.  If after replacing the relay, then its the solnoid on the trans.  Last case and worse scenario would be an internal fault inside the transmission itself.  Roger