My 1992 VOLVO DL 240 was experiencing a shift-interlock problem. Each morning I could not shift from PARK to DRIVE after foot on the brake and depress the shifter top button. After extensive research, VOLVO forum chat, and troubleshooting I can now safely say I no longer have this problem. What I did was the following:

(a) car is OFF and key is out of the ignition. Emergency brake is ON
(b) unscrew (2) Philips screws attaching the plastic shift console to the floor. You will need a small Philips screwdriver as the shifter is in PARK and it is difficult to remove the tiny black screws securing the console to the raised hump
(c) take an air hose and blow into the shifter well. The more air the better. Blow into every "nook and cranny" that contains wires, connectors, and any voids. The solenoid is at bottom w/ the pin engagement to the shifter PARK position so get lots of air into into the well
(d) next spray WD-40 from the top and let it run down the sides of everything in the well. The manual (Yellow) release will feel real easy to toggle after the WD-40 application
(d)blow air again into the well area but insure the WD-40 is not sprayed out and onto the nearby plastic(s). Use a nice soft cotton cloth to wipe any WD-40 found outside the shifter well
(e) realign the plastic shifter console to the raised hump and screw the (2) small screws back to the floor. Ensure the console fits over the rear metallic clip securing the console to the floor
(e) wipe everything off again and check out the SHIFT interlock by starting the vehicle, foot on the brake, and depress the shifter top ****. Ensure the manual release is to the far right. Leave it in this position.

Perhaps I was lucky but I am up to a dozen starts and shifts w/o any problem. My car has 120,000 miles and runs great. Have fun....

abro89
(I love VOLVOs)