Isuzu trooper 3.0 not starting?

hi i have an isuzu trooper its 1999 3.0 dieses i was stopped at traffic lights the other day and it cut out and wont start now .the only thing i have noticed is that the heater light is not coming on when i turn on the key now.i put a multimeter on the wire leading to the heater plugs and there is no power when the key is switched on can anyone help me please as i cant afford to bring it to the isuzu dealer the would charge me 80 euros an hour to fix it so any suggestions would be much appreciated