1999 Dodge Caravan Speedometer, gauges and warning lights

Electrical problem
1999 Dodge Caravan 6 cyl All Wheel Drive Automatic

At random times, the ABS warning light and the Check Engine Warning light will come on. When they do, all of the gauges and the lights in the dash go out. I have found that if I hit a bump or hit the dash in a particular place, they come back on. The problem is worsening where, some times it is a week or more before I can get things working properly again. On 1 such occasion this past week, my husband hit the dash too hard and popped the hand off the speedometer. I need to get the speedometer fixed and also try to find out what could be causing the other issue. Can you tell me a low cost way to get the speedometer fixed and the other problem handled or at least help diagnose the problem?