Fristim,

When you engage the OD, does the OD-light in your dashboard light up ?
If not, you have a broken cableconnection in your stickshift.
Take it apart and remove the switch.
Attached to it is a cable that can break after so many movements, in the bottom.
Although there is not much room to move around in , it is possible to resolder or add an extra lenght of cable.

In my case in happened in two cars and i was able to fix it twice to full satisfaction.

If the a.m. is not applicable, remove the panel under your radio and while engaging and disengaging the OD-switch feel/listen to your OD-relay whether it enganges or not.
If not check it for loose contacts.
If it works, suspect your OD-solenoid.

Most probably you find this item somewhere in th FAQ.

Kind regards from The Netherlands,

John