Cruise control works intermittently. Shut engine off and restart, cruise works.

I am not well versed enough with the Envoy to have seen a common problem with them. It could be many things and intermittent problems are often hard to find. You may want to start tracing the wiring diagram for the circuit after reading an over view of how the system works. There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online