The tachometer is a display that simply shows how many Revolutions Per Minute the motor is turning. So long as your trans is shifting properly, you really don't have to worry about it with an automatic equipped car (unless you want to). There are a lot of things that would cause the tach to quit. It's probably not a fuse. The tach should be fused with the rest of the cluster, that being the case, the whole cluster goes down, not just one gauge. I'm not sure if the wiring on these comes from the distributor via the computer or straight from the distributor. The first thing I'd check is to make sure all the wires going to the distributor are hooked up properly. After that...best bet is to consult a shop manual. It's hard to diagnose and explain in a message that isn't a few thousand words long. If a dis(mis)connected wire isn't it, let me know, and I'll try to walk you through it further. Cheers.