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Hey guys! Long time listener, first time caller! I have a 2003 7.3 F-250. About a year ago my battery light was coming on and off periodically sometimes for a few minutes and sometimes for a few days. But when I got the batteries and alternator checked, they tested fine. And I noticed when I drove in the rain it would try to shut off. Well about 7 months ago I was driving and it just shut off. It would turn over but not crank. So I cracked the fuel filter open and turned it over. No fuel came out so I thought it was the fuel pump. Put a new one one and still nothing. No power to the fuel pump. So a friend put a new ecm on it and it fired right up. But when you drive it about a mile it shuts off frying the ecm. Well I've fried 4 ecm's and its at the 5th mechanic. The other 4 gave up and said they're chasing a ghost. Anybody ever heard of this? So this was so long. Thanks in advance!
 

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Sounds like a ground issue. I would check the PCM grounds - or maybe even re do them all. Check your engine to frame grounds and your frame to chassis grounds. Clean them all. Also, swap the alternator anyway. It is possible that an alternator can put out the required voltage to pass the bench test, but still be putting out some wild aberrant waveforms that will affect sensitive electronics. For example, if one of the rectifiers was failing and allowing an a/c current to pass.
 

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Frying computer

Check the lower windshield on drivers side under black plastic below wipers. Possible rusted out cowl panel leaking into computer. Common issue with older trucks.
You can possibly look up above emergency brake and see if any signs of water or rust streaks.
If you have any rust in cowl area get this fixed asap
Hope this helps, Dan
 
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