Frage Steyr 12M18 Dashboard light problem

Dear Steyr Owners,

I would like to inquire about a dashboard light problem on 12M18. Met somebody with the next problem after i turn on the park light and low beam the dashboard light was not working. After 1,5-3 engine run suddenly the light work again continously. I think the problem with electric plastic box under glove compartment. My theory should be right? Has anybody for that a circuit plan (wiring diagram)?

Thank you in advance!