2009 Chevy Colorado 10 to 15 minutes before it will start. Why does this happen. It started when the truck had only 40,000 miles and now it has 60,000 miles and we have taken it in numerous times and they can't find anything wrong.

The only way this can be discovered is via *hands-on* testing while the failure is present! This may involve leaving vehicle at repair facility until this test can be completed by qualified personnel using the required diagnostic equipment.. Intermittent failures are near impossible for ANYONE to diagnose. Posting a list of the multiple possibilities isn’t beneficial at all as the required testing must be performed for each one - while the failure is present. Sorry but that’s just how it is, Good luck!