Volvo: Gauge cluster lights, gauge cluster, electrical portion

Question
When starting my 94 Volvo 850 the gauge cluster lights come on - what I used to call the dash lights - and then go off while driving.  The individual gauge lights all are OK, but the gauge cluster lights remain out until vehicle is restarted.  Dealer reports that all bulbs are OK.  Replaced electrical portion of ignition switch with no success, tried a new instrument illumination switch with no success and now gauge cluster lights do not even come on upon starting vehicle.

Guess I will have to take it back again; however I would like to be prepared with questions or suggestions provided by you.

Many thanks.

Harris Johnson  

Answer
Harris,
Are the lights you refer to the lights that illuminate the instrument cluster? If yes then trace the wires going to the dash dimmer to see if they are somehow loose or broken. Use a test light and see if you also loose power to the test light. See also if the power coming to the dimmer is also being lost when this happens.
There are no questions to ask just explain what happens to the lights and show them so they know what they are looking for.