What would cause the speedometer and tachometer and heat gauge on a 2001 Nissan Sentra to occasionally stop working for a short time and come back on?

Usually anytime gages or lights act funny meaning they are just not going on or off which would be a powerloss, clean and simple. When you have bad or missing ground wire connections, what you get are under-powered dash lights, head lights, parking lights, and gages that look like theyre at the disco dancing to the wrong beat. This means that the components w/ bad grounds have to ground through different methods i.e... through metal chassis contact or worst of all grounding through a circuit that its not supposed to. That is why you have several indictions whichever circuit has a bad ground it is affecting the nearest circuit by grounding through it which scrambles and fights the energy in the other circuit creating your haywire symptoms. Best thing to do is identify your ground circuits and make sure the connections are good. Sometimes adding extra grounds could be your only solution to what can become a big headache. You'll need a wiring schematic and some basic knowledge of how electricity works. I suggest first some elematary reading on simple ciruits and electrical trouble-shooting before attemping repairs, This stuff is in most vehicle repair manuals,but for the most part bad connections are visible once you find the start and end of the circuit it can be pretty obvious. loose screw or bolt, loose terminal connection, or a hard overheated wire that acts more like resistor (like a dam restricting flow of electrons). Electrons flow like water, kink the pipe and u get less water same with electricity. Hope this helps to get You started on becoming aleast a little more knowledgeable when dealing with electrical issues. Tired connections and wiring are always an issue in older vehicles. Learning how to remedy simple wiring problmes is a must. Unless your vehicle has had electrical fires or severe short circuits what you are dealing with are fatigue induced problems. Age in another word.