On my 2007 Suburban the cruise control sometimes will not engage. Then 30 minutes later it will work fine. It never disengages on its own, so it doesn't behave like a brake switch problem. The first time this happened I was able to pull back on the brake petal and it engaged fine. The brake switch was replaced then and all worked fine. Now its behavior is different. I have had the brake switch replaced two more times and its behavior is the same. I sprayed the connector with contact cleaner which did not make any difference. I had one garage say that it might be the clock spring. All the Chevrolet garage wants to do it replace the brake switch again, all because there is an old code in the computer. But I replaced it just a few weeks ago and still the problem persists.Any help would be greatly appreciated.