A friend's 02 Ram 2500, 360/5 speed: truck was parked for 2 weeks as he was replacing all the brake lines. Fuel tank was dropped to do the rear line. Once the job was complete, it took a while to get running because the system needed to get primed. Got it running, allowed it to warm up, and then shut it down. Ten mins later, went to again start it and no dice. When turning the ignition to the Run position, the Check Engine light flashes. We have verified the coil is good by installing it on my truck, and it ran fine. The fuel pump cycles, all the fuses are good and there are no codes stored according to the scanner.

Any suggestions on what to check? Crank sensor? ECM?