Just purchased an '98 12-valve 3500 4x4 that has a screwed up gauge cluster. The speedo never moves. The odometer blinks or goes out when the truck is running and the tach and the other 4 gauges bounce whenever the truck is running EXCEPT when the e-brake is engaged (even just one click)-then none of them move at all.

Any suggestions where to start hunting for this gremlin? I'll start poking around under the dash this weekend but knowing where to poke would be helpful. Seems to me that the e-brake may be a clue but I don't yet know what all that ties to besides the brake light on the dash.

Thanks in advance for any suggestions or wild guesses.