My furnace shut off sometime overnight. Trane XE 80, now the automatic pilot won't light? I turned off the power, turned the gas switch to off, waited 5 minutes, switched gas back to on and turned power back on. No pilot.

I have reset what I believe are the limit switches, still nothing

Your Trane XE 80 doesn't use a pilot light. It uses an electrical ignition system controlled by it's computer. There are two lift and remove doors on your furnace. The top gives access to the burner assembly. The other will have the blower motor and the computer. On the computer is a small light in one corner of it's housing. There is also a label with what the blink codes mean on the front of the computer. If your furnace is not lighting it is because the electrical igniter has failed, or one of the furnace's safety devices has tripped or failed. Such devices are fail-safe. This means that if they trip or fail in some way they will prevent the furnace from lighting. This is to prevent the furnace operating when it may be faulty and burning your house down. Call a pro