Here the exhaust fan is controlled by a timer instead of a switch. There should be two hot wires and a ground coming out of the timer casing, splice one of these to the hot source. Spice the second to the black, cable wire running to the fan. Splice the source neutral to the white cable wire and the ground to the ground wires. At the fan splice the wires, matching the colors of each.
To wire a 3-way switch circuit that controls both the fan and the light, use this diagram. As with all 3-way circuits, the common on one switch is connected to the hot source wire from the circuit. The common on the second 3-way switch is connected to the hot wires on the fan/light.
In this arrangement a light fixture and exhaust fan are wired to the same source. The light is controlled with a single-pole switch and the fan controlled with a timer as in the previous drawing. The hot source is spliced to each controlling device and the output of the controllers are connected as in the previous diagrams on this page.
The white wire is wrapped with black tape to identify it as hot. The black wire connects the fan to the speed controller. The red wire connects the light to the dimmer.