There are just two hot wires going to the cluster and three grounds supplying it. The grounds do all or most of the switching. You can locate those two hots by color once you look up the pin out page on the connectors in the FSM. I took my cluster partly out and unplugged the two connectors, located the two hots, tested them. You can also trace the copper from those hots and locate gauges, see if a gauge’s two wires are working. Each gauge terminal has a screw head you can test. There are fuses for those two hot wires, check the # 3 in the box in the cab. But there is another one too. That’s all I can remember but your FSM will show the various wires to check. This is where having a paper copy helps.I have a 1997 Dodge Ram 2500 12 valve manual. The speedo and tacho are pegged constantly and all of the other gauges have no reading constantly. The previous owner tried to replace the cluster, and it didn't change anything. How do I fix this?