Q. I am looking for a reason why the cruise control on my 2004 GMC diesel with an automatic transmission does not always engage when I am up to cruising speed. About one out of five times, it will not engage until it is turned completely off. Can you steer me to possible reasons and the fix for this frustrating problem?
— M.H., Lake Lure, North Carolina
A. Since it seems to correct itself if you turn it off and restart it, the problem is likely to be in the electronic controls, rather than the sensors, switches and actuator. Depending on the mileage, your truck should still be under warranty for this.
Ken Freund’s more than three decades of auto-repair experience and 20-plus years of RVing helped him author numerous books and articles on vehicle repair. In addition to RV Clinic and Performance, he writes the Powertrain column in MotorHome magazine. Ken has been a California Automotive VO-Tech and Smog-Test Program Instructor and an ASE-certified Master Automobile Technician.