Volvo '06 670 inverter problem

i have a volvo 06 ,670 with a invertor from volvo is next to the batteries anyway i change the swich and the braker and it still stays on all the time anybody has any ideea wat's going on .it works 2 min.that is stays on all the time i try turn off and on from the swich nothing ,thanks in advance.

 

no sir i was working fine before, it is a dry environment no matter if the truck is off or on is still das the same think i was trying to fix it by myself i have to take it to volvo.the proablem is that their are to expensive and being install by them their are the olny one to work on it.anyway the reasons that i'm asking is that i know that a lots of volvo carry this kind of invertor.