Truck won't crank/start
 

My 2008 Chevy Duramax 2500HD was running fine no problems. It only has 91k miles on it and I am the second owner. I have had the EFI live dsp5 installed on it for nearly a year no problems. I drove to NC and two days later my truck would not start. I ended up taking it to the dealership and they replaced the ECM. I got it back a week later and had it for about 5 days and it happened again. They had it another week and replaced the ECM again. Got it back on a Friday drove it that evening and Saturday morning it happened again. They have now had my truck for nearly 4 weeks and they can't seem to figure out what is wrong. First they said the wiring harness but it was good, then the BCM, then the PCM, then they replaced the security control module which was bad and then they said it may be the ECM again. Talked to them today and they told me that when the service trailer brake system message comes up it will not crank but it will crank when it doesn't. Before they put the first ECM in it I did not have a service trailer brake system message come on at all. Can anyone tell me what could be going on? Since they replaced the ECM the first time I have not reprogrammed anything by the way.