Over the last few weeks, my truck has been showing an engine check light. The light comes on only when the truck has been running for 1/2 hour or so. I am only using the truck for short distances while driving to and from mowing jobs. After completing a lawn, I will attempt to start the truck to head to the next job, and it will NOT START. If I wait for 20 more minutes or so and try again, it will now start. A mechanic came over and placed a scan tool to the computer input and the scan tool was not able to read any data!! If anyone has any ideas of where to begin on a diagnosis I would appreciate it. Note: After the truck sits overnight, the next day the truck will start and usually there is no engine check light on.