How do I find out the schedule for buses from guadalajara, jalisco to colotlan, jalisco or huejucar, jalisco?

Sorry, but most bus schedules cannot be found with a google search.

You'll find the most comprehensive online info on busing in Mexico on my website which is linked below. It includes links to all operating bus company websites. Some of those will be down from time to time.

Neither Colotlan nor Huejucar are served by Primera Plus. These small places may be served by Flecha Amarilla, a good second-class company. However, they no longer have a website. Their URL now takes you to Primera Plus, which is their deluxe-class division. The only other bus company that serves the area and has a website is Omnibus de Mexico and the schedule page of their site is down.

I have almost always found the people working at ticket counters in bus station to be helpful. They will usually be able to direct you a company serving your destination.

Cototlan and Huejucar are in the far northern part of Jalisco and are much closer to the city of Zacatecas than to Guadalajara. The closes place of note is the small city of Jerez de Garcia Salinas. Cototlan and Huejucar lie on highway 23 which connects Gudalajara with Jerez de Garcia Salinas.

You can get to places far more remote than Cototlan and Huejucar by bus and since they are directly on the highway, you probably can go straight from Guadalajara without having to change buses along the way.

Most bus and ferry schedules can be found with a Google search.

Primera Plus covers Jalisco better than most and those are not on the list. Either pick a larger town close by on their site ... or visit the bus stations when you are there for smaller companies

http://www.primeraplus.com.mx/iata/