I originally posted this on the V-10 forum, but I think this might be the proper place. Truck is a F-350, 2000, V-10.
About three weeks ago, I;m in New Mexico andthe transmission downshifts to second and won't go back to third. After the Ford house in Espanola puts in a transmission sensor, it's still not working right and later the PCM won't communicate with the scanner and the truck cranks but won't start. They conclude it needs a new PCM and replaces it. I go on towing a trailer for about 1500 miles.
It works fine for about two weeks and then going down the highway in Texas, the engine shuts down like it has run out of fuel, but it's not. It won't restart. When towed in the mechanics get it started and the scanner doesn't give any answers. Later it stops again and won't start, but will crank. The computer won't communicate with the scanner.
This Ford house finally gets it started again and the computer shows two fuel pump codes and they replace the fuel pump. It goes about 10 miles this time before shutting off again and will not start. Also at this time the computer will not communicate with the scanner. They decide the PCM is bad and replace it.
I have now driven it about 300 miles with no problems, but I'm still having trouble figuring out why I've lost two PCMs in less than a month. Can there be another problem that needs to be fixed before I have to get a third?
My local Ford house is trying to go over everything they can think of to see if there is another problem. They claim it's rare to lose a PCM on a V-10.
Anything you can think of will be appreciated.

 

The next time it happens, instead of replacing the PCM, I wonder what would happen if you just unplugged it, and then plug it back in. Maybe there is a connection problem at the PCM plug.

 

That's something else we will check. I would really like to find the smoking gun in this scenario.

 

Dave,

thanks again for your input. I just got back from the local Ford house and all they could find was a tear in the vacuum hose on the throttle body.
They checked some wiring and connections and still haven't found anything. I guess I will have to drive it and see if anything happens again.
Their best guess was that the first time I had trouble was the Diablo chip going out and causing the faulty shifting. Something happened when repairing that and the PCM got ruined. The 2nd time they believe my fuel pump went out and the PCM replacement was faulty. They are not sure of any of this but it's their best guess with the thing running fine and showing no codes.
I think I have gremlins.