I'm guessing you've tried the obvious, and replaced the bulbs? They're old, and bulbs do burn out. Assuming you've done that, and you know the bulbs are good:
The most common failure point is the dimmer switch on the instrument cluster. Fortunately the most common fix is cheap and easy - rotate the dimmer switch like a crazy person until it starts working. Corrosion builds up on the wires in the dimmer switch and stops the sweep arm from completing a circuit. Turning the dimmer switch up and down and up and down and up and down.
Well, the sweep arm gradually breaks through the corrosion and things start working again. If that doesn't fix it, a new dimmer switch can be had, but they're expensive. The other solution is to remove the instrument cluster, locate the dimmer switch on the back of the cluster, and solder a jumper wire across the points there. Your dimmer switch will no longer dim, but you'll have dash lights.
Friday, December 10th, 2010 AT 8:57 PM