hey, i had this same problem with my civic. luckily i have a service manual for a 94 integra and both cars are the same. the power for the gauge lights is routed through the brightness control, generally that is what is causing the issue. mine would just cut out on me randomly, sometimes at night, and if i pounded the dash they come back on. once i realized the brightness control was suspect, hitting it made the lights come back on, so i would start by replacing that, try a junkyard or something.