1994 Voyager- gauges go out!

My 94 Voyager gauges go out whenever you hit a hard enough bump- gas/speed/tach/temp-all of them. Now here's the trick- if you blow the horn they will come back on most of the time (sometimes you have to wait). I' m sure this is probably a bad ground - does anyone know where to start looking?

Had this problem on an older Voyager. The Dash gauges are on a printed circuit with other pc's connected. On mine the "Daughter cards" started to pull out of the sockets. It took a Plymouth Serviceman 8 hours to find and 2 minutes to fix. (at 80.00 per hour!)