I have a 2004 trailblazer, 4.2, 250,000 miles. Was a daily driver and always kept maintenance and serviced. For the miles it has, it runs (or did) great!! One day on way to town the motor died on my while driving down the road. I rolled into a driveway and kept turning key on and off until it finally started again. Took to mechanic immediately and they said their scanner could not detect anything wrong. Went home. Next morning needed to run errand and it wouldn't start not matter what I did. I've owned this truck for about 10 years and the only thing that weird has happened is the headlights would sometimes go out on me while driving, then come back on. Then that wouldn't happen for another 2 or so years. So anyways, I had truck halled to a mechanic. After a week of looking they said it is the ecm or (brain) so they put a new one in and said Chevy dealership will have to program it. Then, dealership said they couldn't program new brain because there is a short somewhere and it could take years to find? I don't know what to do. I have tried jumping the starter relay with wire and I can get it to crank but it won't start. But the key does nothing but make fuel gauge and temp gauge move. I also don't hear fuel pump come on. Someplace please help me with your knowledge!